Districts in the HA area
| District | Main place | Local authority | Sectors | Postcodes |
|---|---|---|---|---|
| HA0 | London | Brent | 5 | 860 |
| HA1 | Harrow | Harrow | 5 | 960 |
| HA2 | Harrow | Harrow | 6 | 966 |
| HA3 | London | Harrow | 7 | 1,262 |
| HA4 | Ruislip | Hillingdon | 6 | 1,137 |
| HA5 | London | Harrow | 6 | 1,094 |
| HA6 | London | Hillingdon | 4 | 721 |
| HA7 | Stanmore | Harrow | 5 | 847 |
| HA8 | Edgware | Barnet | 7 | 1,402 |
| HA9 | Wembley | Brent | 6 | 1,006 |