diff --git a/.gitignore b/.gitignore
index 33d18401..028bca37 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,6 +18,8 @@ etl/**/*.xls
 etl/**/*.xlsx
 etl/**/*.zip
 
+.DS_Store
+
 # Cache
 app/tilecache/**/*.png
 app/tilecache/**/*.mbtiles
diff --git a/.travis.yml b/.travis.yml
index 8ceb64ee..7449d2ac 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: node_js
 node_js:
-  - 8
+  - 12
 cache: npm
 before_script:
   - cd $TRAVIS_BUILD_DIR/app && npm ci
diff --git a/app/.babelrc b/app/.babelrc
deleted file mode 100644
index 1578f26a..00000000
--- a/app/.babelrc
+++ /dev/null
@@ -1,13 +0,0 @@
-{
-    "plugins": [
-        "@babel/plugin-syntax-jsx",
-        "@babel/plugin-syntax-typescript",
-        [
-            "babel-plugin-typescript-to-proptypes",
-            {
-                "implicitChildren": true,
-                "typeCheck": true
-            }
-        ]
-    ]
-}
\ No newline at end of file
diff --git a/app/map_styles/polygon.xml b/app/map_styles/polygon.xml
index 963f5fd2..0e23cc7c 100644
--- a/app/map_styles/polygon.xml
+++ b/app/map_styles/polygon.xml
@@ -99,33 +99,29 @@
             <PolygonSymbolizer fill="#e7e1ef" />
         </Rule>
         <Rule>
-            <Filter>[size_height] &gt;= 7.73 and [size_height] &lt; 1.138</Filter>
+            <Filter>[size_height] &gt;= 7.73 and [size_height] &lt; 11.38</Filter>
             <PolygonSymbolizer fill="#d4b9da" />
         </Rule>
         <Rule>
-            <Filter>[size_height] &gt;= 1.138 and [size_height] &lt; 1.845</Filter>
+            <Filter>[size_height] &gt;= 11.38 and [size_height] &lt; 18.45</Filter>
             <PolygonSymbolizer fill="#c994c7" />
         </Rule>
         <Rule>
-            <Filter>[size_height] &gt;= 1.845 and [size_height] &lt; 3.505</Filter>
+            <Filter>[size_height] &gt;= 18.45 and [size_height] &lt; 35.05</Filter>
             <PolygonSymbolizer fill="#df65b0" />
         </Rule>
         <Rule>
-            <Filter>[size_height] &gt;= 3.505 and [size_height] &lt; 8.930</Filter>
+            <Filter>[size_height] &gt;= 35.05 and [size_height] &lt; 89.30</Filter>
             <PolygonSymbolizer fill="#e7298a" />
         </Rule>
         <Rule>
-            <Filter>[size_height] &gt;= 8.930 and [size_height] &lt; 15.179</Filter>
+            <Filter>[size_height] &gt;= 89.30 and [size_height] &lt; 152</Filter>
             <PolygonSymbolizer fill="#ce1256" />
         </Rule>
         <Rule>
-            <Filter>[size_height] &gt;= 15.179 and [size_height] &lt; 99.999</Filter>
+            <Filter>[size_height] &gt;= 152</Filter>
             <PolygonSymbolizer fill="#980043" />
         </Rule>
-        <Rule>
-            <Filter>[size_height] &gt;= 99.999</Filter>
-            <PolygonSymbolizer fill="#67001f" />
-        </Rule>
     </Style>
     <Style name="date_year">
         <Rule>
@@ -299,7 +295,7 @@
         </Rule>
         <Rule>
             <Filter>[current_landuse_order] = "Transport"</Filter>
-            <PolygonSymbolizer fill="#b3de69" />
+            <PolygonSymbolizer fill="#bee8ff" />
         </Rule>
         <Rule>
             <Filter>[current_landuse_order] = "Utilities And Infrastructure"</Filter>
diff --git a/app/package-lock.json b/app/package-lock.json
index 80debd79..d886d083 100644
--- a/app/package-lock.json
+++ b/app/package-lock.json
@@ -425,15 +425,6 @@
         "@babel/helper-plugin-utils": "^7.0.0"
       }
     },
-    "@babel/plugin-syntax-typescript": {
-      "version": "7.7.4",
-      "resolved": "https://registry.npmjs.org/@babel/plugin-syntax-typescript/-/plugin-syntax-typescript-7.7.4.tgz",
-      "integrity": "sha512-77blgY18Hud4NM1ggTA8xVT/dBENQf17OpiToSa2jSmEY3fWXD2jwrdVlO4kq5yzUTeF15WSQ6b4fByNvJcjpQ==",
-      "dev": true,
-      "requires": {
-        "@babel/helper-plugin-utils": "^7.0.0"
-      }
-    },
     "@babel/plugin-transform-arrow-functions": {
       "version": "7.2.0",
       "resolved": "https://registry.npmjs.org/@babel/plugin-transform-arrow-functions/-/plugin-transform-arrow-functions-7.2.0.tgz",
@@ -1189,9 +1180,9 @@
       "dev": true
     },
     "@types/node": {
-      "version": "8.10.59",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-8.10.59.tgz",
-      "integrity": "sha512-8RkBivJrDCyPpBXhVZcjh7cQxVBSmRk9QM7hOketZzp6Tg79c0N8kkpAIito9bnJ3HCVCHVYz+KHTEbfQNfeVQ==",
+      "version": "12.12.25",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-12.12.25.tgz",
+      "integrity": "sha512-nf1LMGZvgFX186geVZR1xMZKKblJiRfiASTHw85zED2kI1yDKHDwTKMdkaCbTlXoRKlGKaDfYywt+V0As30q3w==",
       "dev": true
     },
     "@types/nodemailer": {
@@ -2420,17 +2411,6 @@
       "integrity": "sha512-f49NsaohQ1ByY20nUrpc30QFdbeT4ntV4PAL2vSZe6uCB5nqAcqXS/qzU+aI6ZfYhWASx5eIsTFvFrs1B2ffGg==",
       "dev": true
     },
-    "babel-plugin-typescript-to-proptypes": {
-      "version": "0.17.1",
-      "resolved": "https://registry.npmjs.org/babel-plugin-typescript-to-proptypes/-/babel-plugin-typescript-to-proptypes-0.17.1.tgz",
-      "integrity": "sha512-yREUfvDlmn6QjM0QbywXUkXBQMD/iFfLVTl+jig4X7ZLUg9lq8ZLuex8HIM2SQ4X3vcjGnWPFowodlMcXhwxdQ==",
-      "dev": true,
-      "requires": {
-        "@babel/helper-module-imports": "^7.0.0",
-        "@babel/helper-plugin-utils": "^7.0.0",
-        "@babel/plugin-syntax-typescript": "^7.2.0"
-      }
-    },
     "babel-preset-jest": {
       "version": "23.2.0",
       "resolved": "https://registry.npmjs.org/babel-preset-jest/-/babel-preset-jest-23.2.0.tgz",
diff --git a/app/package.json b/app/package.json
index 9794a47e..9c9915f5 100644
--- a/app/package.json
+++ b/app/package.json
@@ -26,7 +26,6 @@
     "node-fs": "^0.1.7",
     "nodemailer": "^6.3.0",
     "pg-promise": "^8.7.5",
-    "prop-types": "^15.7.2",
     "query-string": "^6.8.2",
     "react": "^16.9.0",
     "react-dom": "^16.9.0",
@@ -37,16 +36,13 @@
     "sharp": "^0.22.1"
   },
   "devDependencies": {
-    "@babel/plugin-syntax-jsx": "^7.7.4",
-    "@babel/plugin-syntax-typescript": "^7.7.4",
     "@types/express": "^4.17.2",
     "@types/express-session": "^1.15.16",
     "@types/jest": "^24.0.23",
     "@types/lodash": "^4.14.149",
     "@types/mapbox__sphericalmercator": "^1.1.3",
-    "@types/node": "^8.10.59",
+    "@types/node": "^12.12.25",
     "@types/nodemailer": "^6.2.2",
-    "@types/prop-types": "^15.7.3",
     "@types/react": "^16.9.16",
     "@types/react-dom": "^16.9.4",
     "@types/react-leaflet": "^2.5.0",
@@ -54,7 +50,6 @@
     "@types/sharp": "^0.22.3",
     "@types/webpack-env": "^1.14.1",
     "babel-eslint": "^10.0.3",
-    "babel-plugin-typescript-to-proptypes": "^0.17.1",
     "eslint": "^5.16.0",
     "eslint-plugin-jest": "^22.21.0",
     "eslint-plugin-react": "^7.17.0",
diff --git a/app/public/openapi.yml b/app/public/openapi.yml
new file mode 100644
index 00000000..079ac355
--- /dev/null
+++ b/app/public/openapi.yml
@@ -0,0 +1,155 @@
+openapi: 3.0.0
+info:
+  title: Colouring London API
+  version: 1.0.0
+
+servers:
+  - url: https://colouring.london/api
+    description: Production server (uses live data)
+
+paths:
+
+  /extracts:
+    get:
+      summary: Returns a list of bulk data extracts
+      responses:
+        '200':
+          description: A list of bulk extracts, from newest to oldest
+          content:
+            application/json:
+              schema:
+                properties:
+                  extracts:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/BulkExtract'
+              example:
+                extracts:
+                  - extract_id: 1
+                    extracted_on: 2019-10-03T05:33:00.000Z
+                    download_path: /downloads/data-extract-2019-10-03-06_33_00.zip
+        '400':
+          $ref: '#/components/responses/BadRequest'
+        '500':
+          $ref: '#/components/responses/ServerError'
+
+  /history:
+    get:
+      summary: Returns a paginated list of edits (latest edits if no relevant parameters specified)
+      parameters:
+        - name: before_id
+          description: Returned edits will be ones made directly before the specified revision ID
+          in: query
+          schema:
+            $ref: '#/components/schemas/RevisionId'
+          required: false
+        - name: after_id
+          description: Returned edits will be ones made directly after the specified revision ID
+          in: query
+          schema:
+            $ref: '#/components/schemas/RevisionId'
+          required: false
+        - name: count
+          description: The desired number of records to return
+          in: query
+          schema:
+            type: number
+            minimum: 1
+            maximum: 100
+            default: 100
+          required: false
+      responses:
+        '200':
+          description: A list of edit history records
+          content:
+            application/json:
+              schema:
+                properties:
+                  history:
+                    type: array
+                    items:
+                      $ref: '#/components/schemas/BuildingEditHistoryEntry'
+                  paging:
+                    type: object
+                    properties:
+                      id_for_older_query:
+                        allOf:
+                          - $ref: '#/components/schemas/RevisionId'
+                          - description: If older records exist - ID to use for querying them (use as before_id param), otherwise null
+                            nullable: true
+                      id_for_newer_query:
+                        allOf:
+                          - $ref: '#/components/schemas/RevisionId'
+                          - description: If newer records exist - ID to use for querying them (use as after_id param), otherwise null
+                            nullable: true
+        '400':
+          $ref: '#/components/responses/BadRequest'
+        '500':
+          $ref: '#/components/responses/ServerError'
+
+components:
+  responses:
+    BadRequest:
+      description: Invalid request submitted by user
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+
+    ServerError:
+      description: Unexpected server error
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/Error'
+          example:
+            error: Database error
+
+  schemas:
+    Error:
+      type: object
+      properties:
+        error:
+          type: string
+          description: Error message
+
+    BulkExtract:
+      type: object
+      properties:
+        extract_id:
+          type: integer
+          description: Unique sequential ID for the extract
+        extracted_on:
+          type: string
+          format: date-time
+          description: UTC timestamp at which the extract was generated
+        download_path:
+          type: string
+          description: Download path for the extract. Contains only URL path (should be used with the same hostname as the API).
+
+    RevisionId:
+      description: Unique sequential ID for an edit history entry (positive big integer)
+      type: string
+      pattern: ^[1-9]\d*&
+
+    BuildingEditHistoryEntry:
+      type: object
+      properties:
+        revision_id:
+          $ref: '#/components/schemas/RevisionId'
+        forward_patch:
+          type: object
+          description: Forward diff of the building attribute data
+        reverse_patch:
+          type: object
+          description: Reverse diff of the building attribute data
+        revision_timestamp:
+          type: string
+          format: date-time
+          description: UTC timestamp at which the building data was edited
+        username:
+          type: string
+          description: Username of the editor
+        building_id:
+          type: number
+          description: Unique ID of the edited building
\ No newline at end of file
diff --git a/app/razzle.config.js b/app/razzle.config.js
index 42bd60aa..aa6348cd 100644
--- a/app/razzle.config.js
+++ b/app/razzle.config.js
@@ -9,17 +9,6 @@ module.exports = {
         })
         config.module.rules = rules;
 
-        // find module rule that runs ts-loader for TS(X) files
-        const tsRule = config.module.rules.find(r => 
-            new RegExp(r.test).test('test.tsx') && Array.isArray(r.use) && r.use.some(u => u.loader.includes('ts-loader')));
-
-        // run babel-loader before ts-loader to generate propTypes
-        tsRule.use.push({
-            loader: 'babel-loader',
-            options: {
-                babelrc: true
-            }
-        })
         return config;
     },
 };
diff --git a/app/src/api/api.ts b/app/src/api/api.ts
index 59471b6b..d299e1ef 100644
--- a/app/src/api/api.ts
+++ b/app/src/api/api.ts
@@ -2,13 +2,15 @@ import bodyParser from 'body-parser';
 import express from 'express';
 
 import * as editHistoryController from './controllers/editHistoryController';
+import { ApiParamError, ApiUserError } from './errors/api'; 
+import { DatabaseError } from './errors/general';
 import buildingsRouter from './routes/buildingsRouter';
 import extractsRouter from './routes/extractsRouter';
+import leaderboardRouter from './routes/leaderboardRouter';
 import usersRouter from './routes/usersRouter';
 import { queryLocation } from './services/search';
 import { authUser, getNewUserAPIKey, logout } from './services/user';
 
-
 const server = express.Router();
 
 // parse POSTed json body
@@ -17,6 +19,7 @@ server.use(bodyParser.json());
 server.use('/buildings', buildingsRouter);
 server.use('/users', usersRouter);
 server.use('/extracts', extractsRouter);
+server.use('/leaderboard', leaderboardRouter);
 
 server.get('/history', editHistoryController.getGlobalEditHistory);
 
@@ -93,14 +96,30 @@ server.get('/search', function (req, res) {
     });
 });
 
-server.use((err, req, res, next) => {
+server.use((err: any, req: express.Request, res: express.Response, next: express.NextFunction) => {
     if (res.headersSent) {
         return next(err);
     }
 
     if (err != undefined) {
         console.log('Global error handler: ', err);
-        res.status(500).send({ error: 'Server error' });
+        
+        if (err instanceof ApiUserError) {
+            let errorMessage: string;
+
+            if(err instanceof ApiParamError) {
+                errorMessage = `Problem with parameter ${err.paramName}: ${err.message}`;
+            } else {
+                errorMessage = err.message;
+            }
+
+            res.status(400).send({ error: errorMessage });
+        } else if(err instanceof DatabaseError){
+            res.status(500).send({ error: 'Database error' });
+        } else {
+            res.status(500).send({ error: 'Server error' });
+        }
+        
     }
 });
 
diff --git a/app/src/api/controllers/buildingController.ts b/app/src/api/controllers/buildingController.ts
index 3993b619..0bb6ad23 100644
--- a/app/src/api/controllers/buildingController.ts
+++ b/app/src/api/controllers/buildingController.ts
@@ -1,6 +1,6 @@
 import express from 'express';
 
-import { parseIntParam } from '../helpers';
+import { parsePositiveIntParam, processParam } from '../parameters';
 import asyncController from '../routes/asyncController';
 import * as buildingService from '../services/building';
 import * as userService from '../services/user';
@@ -35,7 +35,7 @@ const getBuildingsByReference = asyncController(async (req: express.Request, res
 
 // GET individual building, POST building updates
 const getBuildingById = asyncController(async (req: express.Request, res: express.Response) => {
-    const buildingId = parseIntParam(req.params.building_id);
+    const buildingId = processParam(req.params, 'building_id', parsePositiveIntParam, true);
 
     try {
         const result = await buildingService.getBuildingById(buildingId);
@@ -63,7 +63,7 @@ const updateBuildingById = asyncController(async (req: express.Request, res: exp
 });
 
 async function updateBuilding(req: express.Request, res: express.Response, userId: string) {
-    const buildingId = parseIntParam(req.params.building_id);
+    const buildingId = processParam(req.params, 'building_id', parsePositiveIntParam, true);
 
     const buildingUpdate = req.body;
 
@@ -84,7 +84,7 @@ async function updateBuilding(req: express.Request, res: express.Response, userI
 
 // GET building UPRNs
 const getBuildingUPRNsById = asyncController(async (req: express.Request, res: express.Response) => {
-    const buildingId = parseIntParam(req.params.building_id);
+    const buildingId = processParam(req.params, 'building_id', parsePositiveIntParam, true);
 
     try {
         const result = await buildingService.getBuildingUPRNsById(buildingId);
@@ -105,7 +105,7 @@ const getBuildingLikeById = asyncController(async (req: express.Request, res: ex
         return res.send({ like: false });  // not logged in, so cannot have liked
     }
 
-    const buildingId = parseIntParam(req.params.building_id);
+    const buildingId = processParam(req.params, 'building_id', parsePositiveIntParam, true);
     
     try {
         const like = await buildingService.getBuildingLikeById(buildingId, req.session.user_id);
@@ -118,7 +118,7 @@ const getBuildingLikeById = asyncController(async (req: express.Request, res: ex
 });
 
 const getBuildingEditHistoryById = asyncController(async (req: express.Request, res: express.Response) => {
-    const buildingId = parseIntParam(req.params.building_id);
+    const buildingId = processParam(req.params, 'building_id', parsePositiveIntParam, true);
 
     try {
         const editHistory = await buildingService.getBuildingEditHistory(buildingId);
@@ -134,7 +134,7 @@ const updateBuildingLikeById = asyncController(async (req: express.Request, res:
         return res.send({ error: 'Must be logged in' });
     }
 
-    const buildingId = parseIntParam(req.params.building_id);
+    const buildingId = processParam(req.params, 'building_id', parsePositiveIntParam, true);
     const { like } = req.body;
 
     try {
diff --git a/app/src/api/controllers/editHistoryController.ts b/app/src/api/controllers/editHistoryController.ts
index c266e7f5..2c8dcc8d 100644
--- a/app/src/api/controllers/editHistoryController.ts
+++ b/app/src/api/controllers/editHistoryController.ts
@@ -1,17 +1,32 @@
 import express from 'express';
 
+import { ApiParamError, ApiUserError } from '../errors/api';
+import { ArgumentError } from '../errors/general';
+import { checkRegexParam, parsePositiveIntParam, processParam } from '../parameters';
 import asyncController from "../routes/asyncController";
 import * as editHistoryService from '../services/editHistory';
 
 const getGlobalEditHistory = asyncController(async (req: express.Request, res: express.Response) => {
+
+    const revisionIdRegex = /^[1-9]\d*$/;
+    const afterId: string = processParam(req.query, 'after_id', x => checkRegexParam(x, revisionIdRegex));
+    const beforeId: string = processParam(req.query, 'before_id', x => checkRegexParam(x, revisionIdRegex));
+    const count: number = processParam(req.query, 'count', parsePositiveIntParam);
+
+    if(afterId != undefined && beforeId != undefined) {
+        throw new ApiUserError('Cannot specify both after_id and before_id parameters');
+    }
+
     try {
-        const result = await editHistoryService.getGlobalEditHistory();
-        res.send({
-            history: result
-        });
+        const result = await editHistoryService.getGlobalEditHistory(beforeId, afterId, count);
+        res.send(result);
     } catch(error) {
-        console.error(error);
-        res.send({ error: 'Database error' });
+        if(error instanceof ArgumentError && error.argumentName === 'count') {
+            const apiErr = new ApiParamError(error.message, 'count');
+            throw apiErr;
+        }
+
+        throw error;
     }
 });
 
diff --git a/app/src/api/controllers/extractController.ts b/app/src/api/controllers/extractController.ts
index 369459be..077d69c5 100644
--- a/app/src/api/controllers/extractController.ts
+++ b/app/src/api/controllers/extractController.ts
@@ -1,6 +1,6 @@
 import express from 'express';
 
-import { parseIntParam } from '../helpers';
+import { parsePositiveIntParam, processParam } from '../parameters';
 import asyncController from '../routes/asyncController';
 import * as dataExtractService from '../services/dataExtract';
 
@@ -15,8 +15,9 @@ const getAllDataExtracts = asyncController(async function(req: express.Request,
 });
 
 const getDataExtract = asyncController(async function(req: express.Request, res: express.Response) {
+    const extractId = processParam(req.params, 'extract_id', parsePositiveIntParam, true);
+    
     try {
-        const extractId = parseIntParam(req.params.extract_id);
         const extract = await dataExtractService.getDataExtractById(extractId);
         res.send({ extract: extract });
     } catch (err) {
diff --git a/app/src/api/controllers/leaderboardController.ts b/app/src/api/controllers/leaderboardController.ts
new file mode 100644
index 00000000..06024597
--- /dev/null
+++ b/app/src/api/controllers/leaderboardController.ts
@@ -0,0 +1,22 @@
+import express from 'express';
+
+import asyncController from "../routes/asyncController";
+import * as leadersService from '../services/leaderboard';
+
+const getLeaders = asyncController(async (req: express.Request, res: express.Response) => {
+    try {
+        const number_limit = req.query.number_limit;
+        const time_limit = req.query.time_limit;
+        const result = await leadersService.getLeaders(number_limit, time_limit);
+        res.send({
+            leaders: result
+        });
+    } catch(error) {
+        console.error(error);
+        res.send({ error: 'Database error' });
+    }
+});
+
+export default{
+    getLeaders
+};
diff --git a/app/src/api/dataAccess/__mocks__/editHistory.ts b/app/src/api/dataAccess/__mocks__/editHistory.ts
new file mode 100644
index 00000000..b4636864
--- /dev/null
+++ b/app/src/api/dataAccess/__mocks__/editHistory.ts
@@ -0,0 +1,62 @@
+import { EditHistoryEntry } from '../../../frontend/models/edit-history-entry';
+import { numAsc, numDesc } from '../../../helpers';
+
+/**
+ * Create an object mocking all method of editHistory dataAccess
+ * The type is set to reflect the type of that module, with added methods
+ * used when testing
+ */
+const mockEditHistory =
+    jest.genMockFromModule('../editHistory') as typeof import('../editHistory') & {
+        __setHistory: (mockHistoryData: EditHistoryEntry[]) => void
+    };
+
+let mockData: EditHistoryEntry[] = [];
+
+mockEditHistory.__setHistory = function(mockHistoryData: EditHistoryEntry[]) {
+    mockData = mockHistoryData.sort(numDesc(x => BigInt(x.revision_id)));
+};
+
+mockEditHistory.getHistoryAfterId = function(id: string, count: number): Promise<EditHistoryEntry[]> {
+    return Promise.resolve(
+        mockData
+            .filter(x => BigInt(x.revision_id) > BigInt(id))
+            .sort(numAsc(x => BigInt(x.revision_id)))
+            .slice(0, count)
+            .sort(numDesc(x => BigInt(x.revision_id)))
+    );
+};
+
+mockEditHistory.getHistoryBeforeId = function(id: string, count: number): Promise<EditHistoryEntry[]> {
+    let filteredData = id == undefined ? mockData : mockData.filter(x => BigInt(x.revision_id) < BigInt(id));
+    return Promise.resolve(
+        filteredData
+            .slice(0, count)
+    );
+};
+
+mockEditHistory.getIdNewerThan = async function(id: string): Promise<string> {
+    const historyAfterId = await mockEditHistory.getHistoryAfterId(id, 1);
+    return historyAfterId[historyAfterId.length - 1]?.revision_id;
+};
+
+mockEditHistory.getIdOlderThan = async function(id: string): Promise<string> {
+    const historyBeforeId = await mockEditHistory.getHistoryBeforeId(id, 1);
+    return historyBeforeId[0]?.revision_id;
+};
+
+const {
+    __setHistory,
+    getHistoryAfterId,
+    getHistoryBeforeId,
+    getIdNewerThan,
+    getIdOlderThan
+} = mockEditHistory;
+
+export {
+    __setHistory,
+    getHistoryAfterId,
+    getHistoryBeforeId,
+    getIdNewerThan,
+    getIdOlderThan
+};
diff --git a/app/src/api/dataAccess/editHistory.ts b/app/src/api/dataAccess/editHistory.ts
new file mode 100644
index 00000000..c500f293
--- /dev/null
+++ b/app/src/api/dataAccess/editHistory.ts
@@ -0,0 +1,88 @@
+import db from '../../db';
+import { EditHistoryEntry } from '../../frontend/models/edit-history-entry';
+import { DatabaseError } from '../errors/general';
+
+const baseQuery = `
+        SELECT
+            log_id as revision_id,
+            forward_patch,
+            reverse_patch,
+            date_trunc('minute', log_timestamp) as revision_timestamp,
+            username,
+            building_id
+        FROM logs
+        JOIN users ON logs.user_id = users.user_id`;
+
+export function getHistoryAfterId(id: string, count: number): Promise<EditHistoryEntry[]> {
+    /** 
+     * SQL with lower time bound specified (records after ID).
+     * The outer SELECT is so that final results are sorted by descending ID
+     * (like the other queries). The inner select is sorted in ascending order
+     * so that the right rows are returned when limiting the result set.
+     */
+    try {
+        return db.any(`
+            SELECT * FROM (
+                ${baseQuery}
+                WHERE log_id > $1
+                ORDER BY revision_id ASC
+                LIMIT $2
+            ) AS result_asc ORDER BY revision_id DESC`,
+            [id, count]
+        );
+    } catch(err) {
+        throw new DatabaseError(err);
+    }
+}
+
+export function getHistoryBeforeId(id: string, count: number): Promise<EditHistoryEntry[]> {
+    try {
+        if(id == undefined) {
+            
+            return db.any(`
+                ${baseQuery}
+                ORDER BY revision_id DESC
+                LIMIT $1
+            `, [count]);
+            
+        } else {
+            
+            return db.any(`
+                ${baseQuery}
+                WHERE log_id < $1
+                ORDER BY revision_id DESC
+                LIMIT $2
+            `, [id, count]);
+        }
+    } catch(err) {
+        throw new DatabaseError(err);
+    }
+}
+
+export async function getIdOlderThan(id: string): Promise<string> {
+    try {
+        const result = await db.oneOrNone<{revision_id:string}>(`
+            SELECT MAX(log_id) as revision_id
+            FROM logs
+            WHERE log_id < $1
+        `, [id]);
+
+        return result?.revision_id;
+    } catch(err) {
+        throw new DatabaseError(err);
+    }
+}
+
+export async function getIdNewerThan(id: string): Promise<string> {
+    try {
+        const result = await db.oneOrNone<{revision_id:string}>(`
+            SELECT MIN(log_id) as revision_id
+            FROM logs
+            WHERE log_id > $1
+        `, [id]);
+
+        return result?.revision_id;
+    } catch(err) {
+        throw new DatabaseError(err);
+    }
+}
diff --git a/app/src/api/errors/api.ts b/app/src/api/errors/api.ts
new file mode 100644
index 00000000..cbc4ba2f
--- /dev/null
+++ b/app/src/api/errors/api.ts
@@ -0,0 +1,44 @@
+/**
+ * Note that custom errors and the instanceof operator in TS work together
+ * only when transpiling to ES2015 and up.
+ * For earier target versions (ES5), a workaround is required:
+ * https://stackoverflow.com/questions/41102060/typescript-extending-error-class
+ */
+
+export class ApiUserError extends Error {
+    constructor(message?: string) {
+        super(message);
+        this.name = 'ApiUserError';
+    }
+}
+
+export class ApiParamError extends ApiUserError {
+    public paramName: string;
+
+    constructor(message?: string, paramName?: string) {
+        super(message);
+        this.name = 'ApiParamError';
+        this.paramName = paramName;
+    }
+}
+
+export class ApiParamRequiredError extends ApiParamError {
+    constructor(message?: string) {
+        super(message);
+        this.name = 'ApiParamRequiredError';
+    }
+}
+
+export class ApiParamOutOfBoundsError extends ApiParamError {
+    constructor(message?: string) {
+        super(message);
+        this.name = 'ApiParamOutOfBoundsError';
+    }
+}
+
+export class ApiParamInvalidFormatError extends ApiParamError {
+    constructor(message?: string) {
+        super(message);
+        this.name = 'ApiParamInvalidFormatError';
+    }
+}
diff --git a/app/src/api/errors/general.ts b/app/src/api/errors/general.ts
new file mode 100644
index 00000000..faacdb41
--- /dev/null
+++ b/app/src/api/errors/general.ts
@@ -0,0 +1,17 @@
+export class ArgumentError extends Error {
+    public argumentName: string;
+    constructor(message?: string, argumentName?: string) {
+        super(message);
+        this.name = 'ArgumentError';
+        this.argumentName = argumentName;
+    }
+}
+
+export class DatabaseError extends Error {
+    public detail: any;
+    constructor(detail?: string) {
+        super();
+        this.name = 'DatabaseError';
+        this.detail = detail;
+    }
+}
diff --git a/app/src/api/helpers.ts b/app/src/api/helpers.ts
deleted file mode 100644
index 4028248c..00000000
--- a/app/src/api/helpers.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-import { strictParseInt } from '../parse';
-
-export function parseIntParam(param: string) {
-    const result = strictParseInt(param);
-    if (isNaN(result)) {
-        throw new Error('Invalid parameter format: not an integer');
-    }
-    return result;
-}
diff --git a/app/src/api/parameters.ts b/app/src/api/parameters.ts
new file mode 100644
index 00000000..865c0947
--- /dev/null
+++ b/app/src/api/parameters.ts
@@ -0,0 +1,44 @@
+import { strictParseInt } from '../parse';
+
+import { ApiParamError, ApiParamInvalidFormatError, ApiParamRequiredError } from './errors/api';
+
+
+export function processParam<T>(params: object, paramName: string, processingFn: (x: string) => T, required: boolean = false) {
+    const stringValue = params[paramName];
+
+    if(stringValue == undefined && required) {
+        const err = new ApiParamRequiredError('Parameter required but not supplied');
+        err.paramName = paramName;
+        throw err;
+    }
+
+    try {
+        return processingFn(stringValue);
+    } catch(error) {
+        if(error instanceof ApiParamError) {
+            error.paramName = paramName;
+        }
+        
+        throw error;
+    }
+}
+
+export function parsePositiveIntParam(param: string) {
+    if(param == undefined) return undefined;
+    
+    const result = strictParseInt(param);
+    if (isNaN(result)) {
+        throw new ApiParamInvalidFormatError('Invalid format: not a positive integer');
+    }
+    return result;
+}
+
+export function checkRegexParam(param: string, regex: RegExp): string {
+    if(param == undefined) return undefined;
+
+    if(param.match(regex) == undefined) {
+        throw new ApiParamInvalidFormatError(`Invalid format: does not match regular expression ${regex}`);
+    }
+    
+    return param;
+}
diff --git a/app/src/api/routes/leaderboardRouter.ts b/app/src/api/routes/leaderboardRouter.ts
new file mode 100644
index 00000000..e0e17c31
--- /dev/null
+++ b/app/src/api/routes/leaderboardRouter.ts
@@ -0,0 +1,9 @@
+import express from 'express';
+
+import leaderboardController from '../controllers/leaderboardController';
+
+const router = express.Router();
+
+router.get('/leaders', leaderboardController.getLeaders);
+
+export default router;
diff --git a/app/src/api/services/__tests__/editHistory.test.ts b/app/src/api/services/__tests__/editHistory.test.ts
new file mode 100644
index 00000000..e8fd2c6e
--- /dev/null
+++ b/app/src/api/services/__tests__/editHistory.test.ts
@@ -0,0 +1,176 @@
+import { EditHistoryEntry } from '../../../frontend/models/edit-history-entry';
+import * as editHistoryData from '../../dataAccess/editHistory'; // manually mocked
+import { ArgumentError } from '../../errors/general';
+import { getGlobalEditHistory } from '../editHistory';
+
+jest.mock('../../dataAccess/editHistory');
+
+const mockedEditHistoryData = editHistoryData as typeof import('../../dataAccess/__mocks__/editHistory');
+
+function generateHistory(n: number, firstId: number = 100) {
+    return [...Array(n).keys()].map<EditHistoryEntry>(i => ({
+        revision_id: (firstId + i) + '',
+        revision_timestamp: new Date(2019, 10, 1, 17, 20 + i).toISOString(),
+        username: 'testuser',
+        building_id: 1234567,
+        forward_patch: {},
+        reverse_patch: {}
+    }));
+}
+
+describe('getGlobalEditHistory()', () => {
+    
+    beforeEach(() => mockedEditHistoryData.__setHistory(generateHistory(20)));
+
+    afterEach(() => jest.clearAllMocks());
+
+    it.each([
+        [null, null],
+        ['100', null],
+        [null, '100']
+    ])('Should error when requesting non-positive number of records', async (beforeId: string, afterId: string) => {
+        let resultPromise = getGlobalEditHistory(beforeId, afterId, 0);
+        await expect(resultPromise).rejects.toBeInstanceOf(ArgumentError);
+        await expect(resultPromise).rejects.toHaveProperty('argumentName', 'count');
+    });
+    
+    describe('getting history before a point', () => {
+
+        it('should return latest history if no ID specified', async () => {
+            const result = await getGlobalEditHistory(null, null, 5);
+
+            expect(result.history.map(x => x.revision_id)).toEqual(['119', '118', '117', '116', '115']);
+        });
+
+        it.each(
+            [
+                [null, 3, ['119', '118', '117']],
+                [null, 6, ['119', '118', '117', '116', '115', '114']],
+                ['118', 1, ['117']],
+                ['104', 10, ['103', '102','101', '100']],
+                ['100', 2, []]
+            ]
+        )('should return the N records before the specified ID in descending order [beforeId: %p, count: %p]', async (
+            beforeId: string, count: number, ids: string[]
+        ) => {
+            const result = await getGlobalEditHistory(beforeId, null, count);
+
+            expect(result.history.map(h => h.revision_id)).toEqual(ids);
+        });
+
+        it.each([
+            [null, 4, null],
+            [null, 10, null],
+            [null, 20, null],
+            [null, 30, null],
+            ['50', 10, '99'],
+            ['100', 10, '99'],
+            ['130', 10, null],
+            ['105', 2, '104'],
+            ['120', 20, null],
+        ])('should detect if there are any newer records left [beforeId: %p, count: %p]', async (
+            beforeId: string, count: number, idForNewerQuery: string
+        ) => {
+            const result = await getGlobalEditHistory(beforeId, null, count);
+
+            expect(result.paging.id_for_newer_query).toBe(idForNewerQuery);
+        });
+
+        it.each([
+            [null, 4, '116'],
+            [null, 10, '110'],
+            [null, 20, null],
+            [null, 30, null],
+            ['50', 10, null],
+            ['100', 10, null],
+            ['130', 10, '110'],
+            ['105', 2, '103'],
+            ['120', 20, null],
+        ])('should detect if there are any older records left [beforeId: %p, count: %p]', async (
+            beforeId: string, count: number, idForOlderQuery: string
+        ) => {
+            const result = await getGlobalEditHistory(beforeId, null, count);
+
+            expect(result.paging.id_for_older_query).toBe(idForOlderQuery);
+        });
+    });
+
+
+    describe('getting history after a point', () => {
+
+        it.each([
+            ['100', 7, ['107', '106', '105', '104', '103', '102', '101']],
+            ['115', 3, ['118', '117', '116']],
+            ['120', 10, []]
+        ])('should return N records after requested ID in descending order [afterId: %p, count: %p]', async (
+            afterId: string, count: number, expected: string[]
+        ) => {
+            const result = await getGlobalEditHistory(null, afterId, count);
+
+            expect(result.history.map(x => x.revision_id)).toEqual(expected);
+        });
+
+        it.each([
+            ['99', 10, '109'],
+            ['110', 5, '115'],
+            ['119', 20, null],
+            ['99', 20, null],
+        ])('should detect if there are any newer records left [afterId: %p, count: %p]', async (
+            afterId: string, count: number, idForNewerQuery: string
+        ) => {
+            const result = await getGlobalEditHistory(null, afterId, count);
+
+            expect(result.paging.id_for_newer_query).toBe(idForNewerQuery);
+        });
+
+        it.each([
+            ['99', 10, null],
+            ['110', 5, '111'],
+            ['119', 20, '120'],
+            ['99', 20, null],
+        ])('should detect if there are any older records left [afterId: %p, count: %p]', async (
+            afterId: string, count: number, idForOlderQuery: string
+        ) => {
+            const result = await getGlobalEditHistory(null, afterId, count);
+
+            expect(result.paging.id_for_older_query).toBe(idForOlderQuery);
+        });
+        
+    });
+
+    describe('result count limit', () => {
+
+        it.each([
+            [null, null],
+            [null, '100'],
+            ['300', null]
+        ])('should not return more than 100 entries (beforeId: %p, afterId: %p)', async (
+            beforeId: string, afterId: string
+        ) => {
+            mockedEditHistoryData.__setHistory(
+                generateHistory(200)
+            );
+
+            const result = await getGlobalEditHistory(beforeId, afterId, 200);
+
+            expect(result.history.length).toBe(100);
+        });
+
+        it.each([
+            [null, null],
+            [null, '100'],
+            ['300', null]
+        ])('should default to 100 entries', async (
+            beforeId: string, afterId: string
+        ) => {
+            mockedEditHistoryData.__setHistory(
+                generateHistory(200)
+            );
+
+            const result = await getGlobalEditHistory(beforeId, afterId);
+
+            expect(result.history.length).toBe(100);
+        });
+
+    });
+});
diff --git a/app/src/api/services/building.ts b/app/src/api/services/building.ts
index 38bbc082..79511324 100644
--- a/app/src/api/services/building.ts
+++ b/app/src/api/services/building.ts
@@ -118,7 +118,7 @@ async function getBuildingById(id: number) {
 async function getBuildingEditHistory(id: number) {
     try {
         return await db.manyOrNone(
-            `SELECT log_id as revision_id, forward_patch, reverse_patch, date_trunc('minute', log_timestamp), username
+            `SELECT log_id as revision_id, forward_patch, reverse_patch, date_trunc('minute', log_timestamp) as revision_timestamp, username
             FROM logs, users
             WHERE building_id = $1 AND logs.user_id = users.user_id
             ORDER BY log_timestamp DESC`,
diff --git a/app/src/api/services/editHistory.ts b/app/src/api/services/editHistory.ts
index 92bf9ca7..81b4c899 100644
--- a/app/src/api/services/editHistory.ts
+++ b/app/src/api/services/editHistory.ts
@@ -1,20 +1,38 @@
-import db from '../../db';
+import { EditHistoryEntry } from '../../frontend/models/edit-history-entry';
+import { decBigInt, incBigInt } from '../../helpers';
+import { getHistoryAfterId, getHistoryBeforeId, getIdNewerThan, getIdOlderThan } from '../dataAccess/editHistory';
+import { ArgumentError } from '../errors/general';
 
-async function getGlobalEditHistory() {
-    try {
-        return await db.manyOrNone(
-            `SELECT log_id as revision_id, forward_patch, reverse_patch, date_trunc('minute', log_timestamp), username, building_id
-            FROM logs, users
-            WHERE logs.user_id = users.user_id
-                AND log_timestamp >= now() - interval '7 days'
-            ORDER BY log_timestamp DESC`
-        );
-    } catch (error) {
-        console.error(error);
-        return [];
+async function getGlobalEditHistory(beforeId?: string, afterId?: string, count: number = 100) {
+    if(count <= 0) throw new ArgumentError('cannot request less than 1 history record', 'count');
+    if(count > 100) count = 100;
+
+    // limited set of records. Expected to be already ordered from newest to oldest
+    let editHistoryRecords: EditHistoryEntry[];
+
+    if(afterId != undefined) {
+        editHistoryRecords = await getHistoryAfterId(afterId, count);
+    } else {
+        editHistoryRecords = await getHistoryBeforeId(beforeId, count);
     }
-}
 
+    const currentBatchMaxId = editHistoryRecords[0]?.revision_id ?? decBigInt(beforeId);
+    const newer = currentBatchMaxId && await getIdNewerThan(currentBatchMaxId);
+
+    const currentBatchMinId = editHistoryRecords[editHistoryRecords.length-1]?.revision_id ?? incBigInt(afterId);
+    const older = currentBatchMinId && await getIdOlderThan(currentBatchMinId);
+
+    const idForOlderQuery = older != undefined ? incBigInt(older) : null;
+    const idForNewerQuery = newer != undefined ? decBigInt(newer) : null;
+
+    return {
+        history: editHistoryRecords,
+        paging: {
+            id_for_newer_query: idForNewerQuery,
+            id_for_older_query: idForOlderQuery
+        }
+    };
+}
 
 export {
     getGlobalEditHistory
diff --git a/app/src/api/services/leaderboard.ts b/app/src/api/services/leaderboard.ts
new file mode 100644
index 00000000..52d6191c
--- /dev/null
+++ b/app/src/api/services/leaderboard.ts
@@ -0,0 +1,39 @@
+import db from '../../db';
+
+async function getLeaders(number_limit: number, time_limit: number) {
+    try {
+        if(time_limit > 0){
+	    return await db.manyOrNone(
+		`SELECT count(log_id) as number_edits, username
+		FROM logs, users
+		WHERE logs.user_id=users.user_id
+		AND CURRENT_TIMESTAMP::DATE - log_timestamp::DATE <= $1
+                AND NOT (users.username = 'casa_friendly_robot') 
+                AND NOT (users.username = 'colouringlondon')
+		GROUP by users.username
+		ORDER BY number_edits DESC
+		LIMIT $2`, [time_limit, number_limit]
+	    );
+			
+	}else{
+	    return await db.manyOrNone(
+		`SELECT count(log_id) as number_edits, username 
+		FROM logs, users 
+		WHERE logs.user_id=users.user_id
+                AND NOT (users.username = 'casa_friendly_robot') 
+                AND NOT (users.username = 'colouringlondon')
+		GROUP by users.username
+		ORDER BY number_edits DESC
+		LIMIT $1`, [number_limit]
+            );
+	}
+    } catch(error) {
+	console.error(error);
+	return [];
+    }
+}
+
+
+export {
+    getLeaders
+};
diff --git a/app/src/frontend/app.tsx b/app/src/frontend/app.tsx
index 6d39803d..2cd49b9d 100644
--- a/app/src/frontend/app.tsx
+++ b/app/src/frontend/app.tsx
@@ -14,6 +14,7 @@ import ContactPage from './pages/contact';
 import ContributorAgreementPage from './pages/contributor-agreement';
 import DataAccuracyPage from './pages/data-accuracy';
 import DataExtracts from './pages/data-extracts';
+import LeaderboardPage from './pages/leaderboard';
 import OrdnanceSurveyLicencePage from './pages/ordnance-survey-licence';
 import OrdnanceSurveyUprnPage from './pages/ordnance-survey-uprn';
 import PrivacyPolicyPage from './pages/privacy-policy';
@@ -113,6 +114,7 @@ class App extends React.Component<AppProps, AppState> {
                 <Route exact path="/data-accuracy.html" component={DataAccuracyPage} />
                 <Route exact path="/data-extracts.html" component={DataExtracts} />
                 <Route exact path="/contact.html" component={ContactPage} />
+                <Route exact path="/leaderboard.html" component={LeaderboardPage} />
                 <Route exact path="/history.html" component={ChangesPage} />
                 <Route exact path={App.mapAppPaths} render={(props) => (
                     <MapApp
diff --git a/app/src/frontend/building/edit-history/building-edit-summary.tsx b/app/src/frontend/building/edit-history/building-edit-summary.tsx
index 2ac230cd..e55399f9 100644
--- a/app/src/frontend/building/edit-history/building-edit-summary.tsx
+++ b/app/src/frontend/building/edit-history/building-edit-summary.tsx
@@ -54,7 +54,7 @@ const BuildingEditSummary: React.FunctionComponent<BuildingEditSummaryProps> = (
 
     return (
         <div className="edit-history-entry">
-            <h2 className="edit-history-timestamp">Edited on {formatDate(parseDate(historyEntry.date_trunc))}</h2>
+            <h2 className="edit-history-timestamp">Edited on {formatDate(parseDate(historyEntry.revision_timestamp))}</h2>
             <h3 className="edit-history-username">By {historyEntry.username}</h3>
             {
                 showBuildingId && historyEntry.building_id != undefined &&
diff --git a/app/src/frontend/header.tsx b/app/src/frontend/header.tsx
index a41f594f..44bf5a74 100644
--- a/app/src/frontend/header.tsx
+++ b/app/src/frontend/header.tsx
@@ -89,6 +89,11 @@ class Header extends React.Component<HeaderProps, HeaderState> {
                                     Downloads
                                 </NavLink>
                             </li>
+                            <li className="nav-item">
+                                <NavLink to="/leaderboard.html" className="nav-link" onClick={this.handleNavigate}>
+                                    Leaderboard
+                                </NavLink>
+                            </li>
                             <li className="nav-item">
                                 <NavLink to="/contact.html" className="nav-link" onClick={this.handleNavigate}>
                                     Contact
diff --git a/app/src/frontend/map/legend.tsx b/app/src/frontend/map/legend.tsx
index 64712384..226c490a 100644
--- a/app/src/frontend/map/legend.tsx
+++ b/app/src/frontend/map/legend.tsx
@@ -26,7 +26,7 @@ const LEGEND_CONFIG = {
             { color: '#f5f58f', text: 'Industry And Business' },
             { color: '#73ccd1', text: 'Community Services' },
             { color: '#ffbfbf', text: 'Recreation And Leisure' },
-            { color: '#b3de69', text: 'Transport' },
+            { color: '#bee8ff', text: 'Transport' },
             { color: '#cccccc', text: 'Utilities And Infrastructure' },
             { color: '#52403C', text: 'Agriculture And Fisheries' },
             { color: '#898944', text: 'Defence' },
@@ -71,13 +71,12 @@ const LEGEND_CONFIG = {
         elements: [
             { color: '#f7f4f9', text: '0-5.55'},
             { color: '#e7e1ef', text: '5.55-7.73'},
-            { color: '#d4b9da', text: '7.73-1.138'},
-            { color: '#c994c7', text: '1.138-1.845'},
-            { color: '#df65b0', text: '1.845-3.505'},
-            { color: '#e7298a', text: '3.505-8.930'},
-            { color: '#ce1256', text: '8.930-15.179'},
-            { color: '#980043', text: '15.179-99.999'},
-            { color: '#67001f', text: '≥99.999'}
+            { color: '#d4b9da', text: '7.73-11.38'},
+            { color: '#c994c7', text: '11.38-18.45'},
+            { color: '#df65b0', text: '18.45-35.05'},
+            { color: '#e7298a', text: '35.05-89.30'},
+            { color: '#ce1256', text: '89.30-152'},
+            { color: '#980043', text: '≥152'}
         ]
     },
     construction: {
diff --git a/app/src/frontend/models/edit-history-entry.ts b/app/src/frontend/models/edit-history-entry.ts
index e0f30d00..6abf13d4 100644
--- a/app/src/frontend/models/edit-history-entry.ts
+++ b/app/src/frontend/models/edit-history-entry.ts
@@ -1,5 +1,5 @@
 export interface EditHistoryEntry {
-    date_trunc: string;
+    revision_timestamp: string;
     username: string;
     revision_id: string;
     forward_patch: object;
diff --git a/app/src/frontend/pages/changes.css b/app/src/frontend/pages/changes.css
new file mode 100644
index 00000000..9ee45613
--- /dev/null
+++ b/app/src/frontend/pages/changes.css
@@ -0,0 +1,7 @@
+.edit-history-link {
+    margin-top: 4em;
+}
+
+.edit-history-latest-link {
+    float: right;
+}
\ No newline at end of file
diff --git a/app/src/frontend/pages/changes.tsx b/app/src/frontend/pages/changes.tsx
index 6f0d7cc5..01af54d5 100644
--- a/app/src/frontend/pages/changes.tsx
+++ b/app/src/frontend/pages/changes.tsx
@@ -1,31 +1,88 @@
+import { parse } from 'query-string';
 import React, { useEffect, useState } from 'react';
+import { Link, RouteComponentProps } from 'react-router-dom';
+
+import './changes.css';
 
 import { apiGet } from '../apiHelpers';
 import { BuildingEditSummary } from '../building/edit-history/building-edit-summary';
+import ErrorBox from '../components/error-box';
 import InfoBox from '../components/info-box';
 import { EditHistoryEntry } from '../models/edit-history-entry';
 
-const ChangesPage = () => {
-    const [history, setHistory] = useState<EditHistoryEntry[]>(undefined);
+interface PagingInfo {
+    id_for_older_query: string;
+    id_for_newer_query: string;
+}
+
+const recordsPerPage = 20;
+
+const ChangesPage = (props: RouteComponentProps) => {
+    const { after_id, before_id } = parse(props.location.search);
+
+    const [history, setHistory] = useState<EditHistoryEntry[]>();
+    const [paging, setPaging] = useState<PagingInfo>();
+    const [error, setError] = useState();
 
     useEffect(() => {
         const fetchData = async () => {
-            const {history} = await apiGet(`/api/history`);
+            setHistory(null);
+            setPaging(null);
+
+            let url = `/api/history?count=${recordsPerPage}`;
+            if(after_id) {
+                url = `${url}&after_id=${after_id}`;
+            }
+            
+            if (before_id) {
+                url = `${url}&before_id=${before_id}`;
+            }
+            try {
+                const {history, paging, error} = await apiGet(url);
+
+                if(error) {
+                    setError(error);
+                } else {
+                    setHistory(history);
+                    setPaging(paging);
+                }
+            } catch (err) {
+                setError('Connection problem. Please try again later...');
+            }
 
-            setHistory(history);
         };
 
         fetchData();
-    }, []);
+    }, [props.location.search]);
     
     return (
         <article>
             <section className="main-col">
                 <h1>Global edit history</h1>
 
+                {
+                    paging?.id_for_newer_query &&
+                        <Link className='edit-history-link' to={`?after_id=${paging.id_for_newer_query}`}>Show more recent changes</Link>
+                }
+                {
+                    (after_id || before_id) &&
+                        <Link className='edit-history-latest-link' to='?'>Show latest changes</Link>
+                }
                 <ul className="edit-history-list">
-                    {(history == undefined || history.length == 0) ?
-                        <InfoBox msg="No changes in the last week"></InfoBox> :
+                    {
+                        error &&
+                            <ErrorBox msg={error}></ErrorBox>
+                    }
+                    {
+                        error == undefined && history == undefined &&
+                            <InfoBox msg="Loading history..."></InfoBox>
+                    }
+                    {
+                        (history?.length === 0) &&
+                            <InfoBox msg="No changes so far"></InfoBox>
+                    }
+                    {   
+                        (history != undefined && history.length > 0) &&
                         history.map(entry => (
                             <li key={`${entry.revision_id}`} className="edit-history-list-element">
                                 <BuildingEditSummary
@@ -37,6 +94,10 @@ const ChangesPage = () => {
                         ))
                     }
                 </ul>
+                {
+                    paging?.id_for_older_query &&
+                        <Link to={`?before_id=${paging.id_for_older_query}`}>Show older changes</Link>
+                }
             </section>
         </article>
     );
diff --git a/app/src/frontend/pages/leaderboard.css b/app/src/frontend/pages/leaderboard.css
new file mode 100644
index 00000000..e89a487f
--- /dev/null
+++ b/app/src/frontend/pages/leaderboard.css
@@ -0,0 +1,34 @@
+table {
+    table-layout: fixed;
+    width: 60%;
+    margin-left: 20%;
+    margin-right: 20%;
+    border: 1px solid black;
+}
+
+table th, td {
+    border: 1px solid black;
+    text-align: left;
+    padding-left: 1%;
+}
+
+table tr:nth-child(odd) {
+    background: #f6f8fa;
+}
+
+table tr:nth-child(1) {
+    background: #fff;
+}
+
+#title {
+    text-align: center;
+    padding-bottom: 1%; 
+}
+
+#radiogroup {
+    padding: 1%;
+}
+
+input[type="radio"] {
+    margin: 0 2px 0 10px;
+}
diff --git a/app/src/frontend/pages/leaderboard.tsx b/app/src/frontend/pages/leaderboard.tsx
new file mode 100644
index 00000000..5ec6612d
--- /dev/null
+++ b/app/src/frontend/pages/leaderboard.tsx
@@ -0,0 +1,149 @@
+import React, { Component } from 'react';
+
+import './leaderboard.css';
+
+    interface Leader {
+        number_edits: string;
+        username: string;
+    }
+
+
+    interface LeaderboardProps {
+    }
+
+
+    interface LeaderboardState {
+        leaders: Leader[];
+        fetching: boolean;
+
+        //We need to track the state of the radio buttons to ensure their current state is shown correctly when the view is (re)rendered
+        number_limit: number;
+        time_limit: number;
+    }
+
+
+class LeaderboardPage extends Component<LeaderboardProps, LeaderboardState> {
+
+    constructor(props) {
+        super(props);
+        this.state = {
+	    leaders: [],
+	    fetching: false,
+            number_limit: 10,
+            time_limit: -1
+        };
+       this.getLeaders = this.getLeaders.bind(this);
+       this.renderTableData = this.renderTableData.bind(this);		
+       this.handleChange = this.handleChange.bind(this);
+    }
+
+	
+    handleChange(e) {
+        if(e.target.name == 'number_limit'){
+            this.getLeaders(e.target.value, this.state.time_limit);
+            this.setState({number_limit: e.target.value});
+	}else {
+            this.getLeaders(this.state.number_limit, e.target.value);
+	    this.setState({time_limit: e.target.value});
+        }
+    }
+	
+	
+    componentDidMount() { 
+	this.getLeaders(this.state.number_limit, this.state.time_limit);
+    }
+
+
+    componentWillUnmount() {}
+		
+	
+    getLeaders(number_limit, time_limit) {
+        
+        this.setState({
+            fetching: true
+        });
+
+        fetch(
+            '/api/leaderboard/leaders?number_limit=' + number_limit + '&time_limit='+time_limit
+        ).then(
+            (res) => res.json()
+        ).then((data) => {
+            if (data && data.leaders){
+                this.setState({
+                    leaders: data.leaders,
+                    fetching: false
+                });
+		
+            } else {
+                console.error(data);
+
+                this.setState({
+                    leaders: [],
+                    fetching: false
+                });
+            }
+        }).catch((err) => {
+            console.error(err);
+
+            this.setState({
+                leaders: [],
+                fetching: false
+            });
+        });
+    }
+	
+	
+    renderTableData() {
+        return this.state.leaders.map((u, i) => {
+	    const username = u.username;             
+            const number_edits = u.number_edits;
+         
+	    return (
+		<tr key={username}>
+                    <td>{i+1}</td>
+		    <td>{username}</td>
+		    <td>{number_edits}</td>
+		</tr>
+	    );
+      });
+   }
+
+
+    render() {
+	return(
+            <div>
+                <form id="radiogroup">    
+                    <div id="number-radiogroup" >
+			<p>Select number of users to be displayed: <br/>
+                            <input type="radio" name="number_limit" value="10" onChange={this.handleChange} checked={10 == this.state.number_limit} />10
+                            <input type="radio" name="number_limit" value="100" onChange={this.handleChange} checked={100 == this.state.number_limit} />100
+                        </p>
+                    </div>
+                    <div id="time-radiogroup" >
+                        <p>Select time period: <br/>
+                            <input type="radio" name="time_limit" value="-1" onChange={this.handleChange}  checked={-1 == this.state.time_limit} /> All time
+			    <input type="radio" name="time_limit" value="7" onChange={this.handleChange}  checked={7 == this.state.time_limit} /> Last 7 days
+                            <input type="radio" name="time_limit" value="30" onChange={this.handleChange}  checked={30 == this.state.time_limit} /> Last 30 days
+                        </p>
+                    </div>
+                </form>      
+                <h1 id='title'>Leader Board</h1>
+                <table id='leaderboard'>
+                    <tbody>
+                        <tr>
+                            <th>Rank</th>
+                            <th>Username</th>
+                            <th>Contributions</th>
+                        </tr>
+                        {this.renderTableData()}
+                    </tbody>
+                </table>
+            </div>		
+	);
+    }
+
+}
+
+
+export default LeaderboardPage;
+
diff --git a/app/src/frontend/styles/layout.css b/app/src/frontend/styles/layout.css
index bf7951ba..f1624c6b 100644
--- a/app/src/frontend/styles/layout.css
+++ b/app/src/frontend/styles/layout.css
@@ -49,6 +49,11 @@ article .color-block {
     padding-left: 1em;
     padding-right: 1em;
 }
+@media(min-width: 768px) {
+    .main-col {
+        min-width: 48em;
+    }
+}
 hr {
     display: block;
     height: 1px;
diff --git a/app/src/helpers.ts b/app/src/helpers.ts
index 372001e1..905b59d9 100644
--- a/app/src/helpers.ts
+++ b/app/src/helpers.ts
@@ -34,3 +34,27 @@ export function isNullishOrEmpty(obj: any) {
 export function isEmptyArray(obj: any) {
     return Array.isArray(obj) && obj.length === 0;
 }
+
+type AccessorFunction<T, V> = (obj: T) => V;
+
+type CompareFunction<T> = (a: T, b: T) => number;
+
+export function numAsc<T, V extends number | bigint>(accessor: AccessorFunction<T, V>): CompareFunction<T>{
+    return (a: T, b: T) => Number(accessor(a) - accessor(b));
+}
+
+export function numDesc<T, V extends number | bigint>(accessor: AccessorFunction<T, V>): CompareFunction<T> {
+    return (a: T, b: T) => Number(accessor(b) - accessor(a));
+}
+
+/** 
+ * As of Jan 2020, bigint literals e.g. 1n can only be used with TS target esnext
+ * which then doesn't transpile the null conditional/coalescing operators and breaks on Node 12
+ * So BigInt(1) needs to be used here
+ * */ 
+export function incBigInt(bigStr: string): string {
+    return bigStr == undefined ? bigStr : String(BigInt(bigStr) + BigInt(1));
+}
+export function decBigInt(bigStr: string): string {
+    return bigStr == undefined ? bigStr : String(BigInt(bigStr) - BigInt(1));
+}
diff --git a/docs/adding-new-fields.md b/docs/adding-new-fields.md
index f487ad7d..a6e07dce 100644
--- a/docs/adding-new-fields.md
+++ b/docs/adding-new-fields.md
@@ -1,4 +1,4 @@
-## Adding new building attribute fields
+# Adding new building attribute fields
 
 This document is a checklist for adding a new building attribute to the system. It's split into three sections - actions that apply when adding any field, and additional steps to add a field that will be visualised on the map.
 The second section would be required when adding a new category or when changing which field should be visualised for a category.
@@ -9,42 +9,42 @@ When adding a new attribute a set of seed data should be identified, the base da
 - Test the API and database elements.
 
 
-### Adding any attribute
+## Adding any attribute
 
-#### In database
+### In database
 1. Add a column to the `buildings` table in the database.
 2. Add any check constraints or foreign key constraints on the column, if necessary (if the foreign key constraint is used to restrict the column to a set of values, the table with the values might need to be created from scratch)
 3. If a source is being collected for field. Add a column `fieldName_source` to the `sources` table. 
 4. If verfication is being enabled. Add a column `bieldName_verifications` to the `verfication` table.
 
 
-#### In API
+### In API
 1. Add field name to `BUILDING_FIELD_WHITELIST` in the building service to allow saving changes to the field
 2. Add any special domain logic for processing updates to the field in the `processBuildingUpdate()` function
 
-#### In frontend
+### In frontend
 1. Add the field description to the `dataFields` object in `data_fields.ts`
 2. Add the data entry React component of the appropriate type (text, numeric etc) to the appropriate category view component in the `building/data-containers` folder. Link to `dataFields` for static string values (field name, description etc)
 
 
-#### In data extracts
+### In data extracts
 1. Add the field to the select list in the COPY query in `maintenance/extract_data/export_attributes.sql` 
 2. Add a description of the field to the `README.txt` file
 
-### Adding an attribute which is used to colour the map
+## Adding an attribute which is used to colour the map
 
 All steps from the previous section need to be carried out first.
 
-#### In tileserver
-1. Add a SQL query for calculating the value to be visualised to `BUILDING_LAYER_DEFINITIONS` in `app/tiles/dataDefinition.ts`
+### In tileserver
+1. Add a SQL query for calculating the value to be visualised to `BUILDING_LAYER_DEFINITIONS` in `app/src/tiles/dataDefinition.ts`
 2. Add Mapnik rendering style in `app/map_styles/polygon.xml`
 
-#### In frontend
+### In frontend
 1. Update the category to field name mapping in the `tilesetByCat` object inside the `ColouringMap` React component (`map.tsx` file)
 2. Add an entry for the field to the `LEGEND_CONFIG` object in `legend.tsx` file
 
 
-### Testing 
+## Testing 
 
 Run tests on staging to confirm;
 - Database changes accepted
diff --git a/docs/setup-dev-environment.md b/docs/setup-dev-environment.md
index 8317b969..97a95c1e 100644
--- a/docs/setup-dev-environment.md
+++ b/docs/setup-dev-environment.md
@@ -37,7 +37,7 @@ Now clone the colouring london codebase.
 Now install Node. It is helpful to define some local variables.
 
 ```
-NODE_VERSION=v8.11.3
+NODE_VERSION=v12.14.1
 DISTRO=linux-x64
 wget -nc https://nodejs.org/dist/$NODE_VERSION/node-$NODE_VERSION-$DISTRO.tar.xz
 sudo mkdir /usr/local/lib/node
@@ -137,7 +137,7 @@ root user profile. Don't forget to exit from root at the end.
 
 ```
 sudo su root
-export NODEJS_HOME=/usr/local/lib/node/node-v8.11.3/bin/`
+export NODEJS_HOME=/usr/local/lib/node/node-v12.14.1/bin/`
 export PATH=$NODEJS_HOME:$PATH`
 npm install -g npm@next`
 exit
diff --git a/docs/setup-production-environment.md b/docs/setup-production-environment.md
index cb4a84d6..3e232d48 100644
--- a/docs/setup-production-environment.md
+++ b/docs/setup-production-environment.md
@@ -72,7 +72,7 @@ Now set appropriate permissions on the `colouring-london` directory
 
 First define a couple of convenience variables:
 
-`NODE_VERSION=v8.11.3`
+`NODE_VERSION=v12.14.1`
 
 `DISTRO=linux-x64`
 
@@ -111,7 +111,7 @@ Now upgrade the `npm` package manager to the most recent release with global pri
 
 `sudo su root`
 
-`export NODEJS_HOME=/usr/local/lib/node/node-v8.11.3/bin/`
+`export NODEJS_HOME=/usr/local/lib/node/node-v12.14.1/bin/`
 
 `export PATH=$NODEJS_HOME:$PATH`
 
@@ -244,7 +244,7 @@ Perform a global install of PM2
 
 `sudo su root`
 
-`export NODEJS_HOME=/usr/local/lib/node/node-v8.11.3/bin/`
+`export NODEJS_HOME=/usr/local/lib/node/node-v12.14.1/bin/`
 
 `export PATH=$NODEJS_HOME:$PATH`
 
diff --git a/etl/join_building_data/load_csv.py b/etl/join_building_data/load_csv.py
index d7927c34..0afebe14 100644
--- a/etl/join_building_data/load_csv.py
+++ b/etl/join_building_data/load_csv.py
@@ -60,9 +60,14 @@ def main(base_url, api_key, source_file, json_columns):
             if building_id is None:
                 continue
 
+            if 'sust_dec' in line and line['sust_dec'] == '':
+                del line['sust_dec']
+
             response_code, response_data = update_building(building_id, line, api_key, base_url)
             if response_code != 200:
                 print('ERROR', building_id, response_code, response_data)
+            else:
+                print('DEBUG', building_id, response_code, response_data)
 
 
 def update_building(building_id, data, api_key, base_url):
@@ -82,6 +87,7 @@ def find_building(data, base_url):
         if building_id is not None:
             print("match_by_building_id", building_id)
             return building_id
+
     if 'toid' in data:
         building_id = find_by_reference(base_url, 'toid', data['toid'])
         if building_id is not None:
diff --git a/etl/join_building_data/load_csv_to_staging.py b/etl/join_building_data/load_csv_to_staging.py
index 413cd533..1b61e90d 100644
--- a/etl/join_building_data/load_csv_to_staging.py
+++ b/etl/join_building_data/load_csv_to_staging.py
@@ -61,6 +61,11 @@ def update_building(building_id, data, api_key, base_url):
 
 
 def find_building(data, base_url):
+    if 'building_id' in data:
+        building_id = data['building_id']
+        if building_id is not None:
+            print("match_by_building_id", building_id)
+            return building_id
     if 'toid' in data:
         building_id = find_by_reference(base_url, 'toid', data['toid'])
         if building_id is not None:
diff --git a/migrations/0xx.team.down.sql b/migrations/0xx.team.down.sql
new file mode 100644
index 00000000..6d34b6de
--- /dev/null
+++ b/migrations/0xx.team.down.sql
@@ -0,0 +1,3 @@
+-- Remove team fields, update in paralell with adding new fields
+-- Award or awards (may be multiple) stored as json b object
+ALTER TABLE buildings DROP COLUMN IF EXISTS team_awards;
diff --git a/migrations/0xx.team.up.sql b/migrations/0xx.team.up.sql
new file mode 100644
index 00000000..ac9868f3
--- /dev/null
+++ b/migrations/0xx.team.up.sql
@@ -0,0 +1,8 @@
+--Storing as json b, create column defined as jsonb
+--This contains the award name and award year
+ALTER TABLE buildings
+    ADD COLUMN IF NOT EXISTS team_awards jsonb;
+
+--To validate this input, the following confirms it's an valid object but not that the items in the object are validated agains those we will acccept
+ALTER TABLE buildings
+    ADD CONSTRAINT data_is_valid CHECK (is_jsonb_valid ('{"type": "object"}', team_awards));
diff --git a/provision/vm_provision.sh b/provision/vm_provision.sh
index 4d6428ab..1ac221b6 100644
--- a/provision/vm_provision.sh
+++ b/provision/vm_provision.sh
@@ -40,7 +40,7 @@ apt-get install -y \
 #
 
 # node version and platform
-NODE_VERSION=v8.11.3
+NODE_VERSION=v12.14.1
 DISTRO=linux-x64
 
 # download