12 Anti-Aircraft Z Regiment RA was formed in March 1941 with three batteries. It formed at Lavernoch, Penarth, Glamorgan. The Regiment disbanded in November 1943.
| Mar 41 | Formed | Penarth, Glamorgan, UK | |
| Mar 41 |  |
6 Anti-Aircraft Division, 56 Anti-Aircraft Brigade | South East England |
| Jan 42 | |
6 Anti-Aircraft Division, 28 Anti-Aircraft Brigade | South East England |
| Oct 42 |  |
1 Anti-Aircraft Group, 28 Anti-Aircraft Brigade | South East England |
| Oct 43 | Disbanded, batteries became independent |
Batteries
| Mar 41 | 101, 111, 124 |
| Aug 41 | 111, 124, 126 |
| Sep 41 | 111, 124, 126, 178 |
| Oct 42 | 124, 178, 196, 211 |
| Dec 42 | 124, 178, 196, 211, 232 |
| Aug 43 | 124, 178, 211, 232 |
Batteries manned by Home Guard
| Battery | Home Guard Unit | Date from |
| 196 Battery | 102 Essex (Mixed) | Jul 42 |
| 211 Battery | 101 Essex (Mixed) | Jul 42 |
| 232 Battery | 102 Kent (Mixed) | Dec 42 |
Gun Sites Occupied
196 Z Battery
| Dates | Gun Site | Gun Defended Area |
| Dec 42 | Abbey Field with 171 Z Battery | Colchester |