| Postcode | Country | County | Type | Status |
|---|---|---|---|---|
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Large | Terminated December 1997 | |
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Large | Terminated May 1994 | |
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Large | Terminated June 1999 | |
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Large | Terminated June 1997 | |
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | (pseudo) England (UA/MD/LB) | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | Terminated August 2010 | |
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small |