| Road Name | Postcode Area | Postcode District | Postcode Sector |
|---|---|---|---|
| Welwyn Avenue | BD | BD18 | BD18 1 |
| Welwyn Avenue | DE | DE22 | DE22 2 |
| Welwyn Avenue | DE | DE24 | DE24 9 |
| Welwyn Avenue | NE | NE22 | NE22 7 |
| Welwyn Avenue | NG | NG19 | NG19 9 |
| Welwyn Avenue | PR | PR8 | PR8 3 |
| Welwyn Avenue | TW | TW14 | TW14 9 |
| Welwyn Avenue | WF | WF17 | WF17 8 |