| Postcode | Country | County | Type | Status |
|---|---|---|---|---|
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Large | Terminated September 2000 | |
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | (pseudo) England (UA/MD/LB) | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | ||
| England | Hertfordshire | Small | Terminated October 2014 | |
| England | Hertfordshire | Large | Terminated December 1992 | |
| England | Hertfordshire | Large | Terminated June 2001 | |
| England | Hertfordshire | Large | Terminated June 2008 | |
| England | Hertfordshire | Large | Terminated June 2014 | |
| England | Hertfordshire | Small |