Regulation 3
| District | Postal Area |
|---|---|
| Bath | BA |
| Birmingham | B |
| Blackburn | BB |
| Bolton | BL |
| Bournemouth | BH |
| Bradford | BD |
| Brighton | BN |
| Bristol | BS |
| Bromley | BR |
| Cambridge | CB |
| Canterbury | CT |
| Cardiff | CF |
| Carlisle | CA |
| Chelmsford | CM |
| Chester | CH |
| Cleveland (Teesside) | TS |
| Colchester | CO |
| Coventry | CV |
| Crewe | CW |
| Croydon | CR |
| Darlington | DL |
| Dartford | DA |
| Derby | DE |
| Doncaster | DN |
| Dorchester | DT |
| Dudley | DY |
| Durham | DH |
| Enfield | EN |
| Exeter | EX |
| Fylde (Blackpool) | FY |
| Gloucester | GL |
| Guildford | GU |
| Halifax | HX |
| Harrogate | HG |
| Harrow | HA |
| Hemel Hempstead | HP |
| Hereford | HR |
| Huddersfield | HD |
| Hull | HU |
| Ilford | IG |
| Ipswich | IP |
| Kingston upon Thames | KT |
| Lancaster | LA |
| Leeds | LS |
| Leicester | LE |
| Lincoln | LN |
| Liverpool | L |
| Llandridnod Wells | LD |
| Llandudno | LL |
| London East | E |
| London East Central | EC |
| London North | N |
| London North West | NW |
| London South East | SE |
| London South West | SW |
| London West | W |
| London West Central | WC |
| Luton | LU |
| Manchester | M |
| Medway | ME |
| Milton Keynes | MK |
| Newcastle | NE |
| Newport | NP |
| Northampton | NN |
| Norwich | NR |
| Nottingham | NG |
| Oldham | OL |
| Oxford | OX |
| Peterborough | PE |
| Plymouth | PL |
| Portsmouth | PO |
| Preston | PR |
| Reading | RG |
| Redhill | RH |
| Romford | RM |
| Salisbury | SP |
| Sheffield | S |
| Shrewsbury | SY |
| Slough | SL |
| Southall (Uxbridge) | UB |
| Southampton | SO |
| Southend on Sea | SS |
| St. Albans | AL |
| Stevenage | SG |
| Stockport | SK |
| Stoke on Trent | ST |
| Sunderland | SR |
| Sutton | SM |
| Swansea | SA |
| Swindon | SN |
| Taunton | TA |
| Telford | TF |
| Tonbridge | TN |
| Torquay | TQ |
| Truro | TR |
| Twickenham | TW |
| Wakefield | WF |
| Walsall | WS |
| Warrington | WA |
| Watford | WD |
| Wigan | WN |
| Wolverhampton | WV |
| Worcester | WR |
| York | YO |