12 (Finsbury Rifles) Light Anti-Aircraft Regiment RA(TA) was formed by the expansion of 224 Battery, 61 Anti-Aircraft Brigade in October 1938. It was initially 12 Anti-Aircraft Brigade but was re-designated to Regiment in January 1939. The Regiment was converted to 12 (Light Anti-Aircraft) Holding Regiment in November 1945. It went into suspended animation in March 1946 at Gosfield Airfield, Colchester. It was re-constituted in January 1947 as 512 (Finsbury Rifles) Light Anti-Aircraft Regiment RA(TA).
| Oct 38 | Formed from a battery of 61 Anti-Aircraft Brigade | |
| Sep 39 | London District | Pentonville, London, UK |
| Oct 39 | 56 Light Anti-Aircraft Brigade, 6 Anti-Aircraft Division | South East Airfields. UK |
| 1940 | 6 Anti-Aircraft Brigade, 6 Anti-Aircraft Division | Essex Airfields, UK |
| May 41 | 60 Anti-Aircraft Brigade, 8 Anti-Aircraft Division | Exeter area, Devon, UK |
| May 42 | 8 Anti-Aircraft Brigade, 10 Army | Persia (Iran) |
| Sep 42 | PAI Force | Iraq |
| May 43 | Middle East Forces | N Africa |
| Jul 43 | 8 Army | Tunisia |
| Jul 43 | 8 Army | Sicily |
| Sep 43 | 8 Army | Italy |
| Mar 45 | 66 Anti-Aircraft Brigade | Italy |
Batteries
| Oct 38 | 34, 35, 36 |
| Jan 39 | 34, 35, 36, 44 |
| Feb 40 | 34, 35, 36 |
| Nov 45 | A, B, C, D |
