2 Heavy Anti-Aircraft Regiment RA was re-designated as 2 Anti-Aircraft Regiment RA from 2 Anti-Aircraft Brigade RA in May 1938. It was re-designated as Heavy Anti-Aircraft in June 1940. The Regiment went to France in 1939 with the BEF. It moved to Egypt in September 1940 and fought in the Middle East and Greece. In April 1947 2 Heavy Anti-Aircraft Regiment RA became 21 Heavy Anti-Aircraft Regiment RA.
Illustrations of the formation badges under which a unit served or supported are given. This is no guarantee that the unit used this formations badge.
| May 38 |  |
3 Anti-Aircraft Division, 3 Anti-Aircraft Brigade | Lichfield, Staffordshire, UK |
| Nov 39 | GHQ BEF, 2 Anti-Aircraft Brigade | Boulogne, France | |
| May 40 | Home Forces | Aberporth, Dyfed, UK | |
| Sep 40 |  |
British Troops Egypt | Mersa Matruh, Egypt |
| Feb 41 |  |
1 Australian Corps | Piraeus, Greece |
| May 41 | |
British Troops Egypt | Alexandria, Egypt |
| Aug 41 | |
British Troops Egypt | N Africa |
| Jan 43 | Diluted with African Pioneer Corps men | ||
| Mar 43 |  |
8 Army | Benghazi, Libya |
| May 43 |  |
GHQ Middle East, 21 Anti-Aircraft Brigade | Suez Canal, Egypt |
| Jul 43 | |
GHQ Middle East, 21 Anti-Aircraft Brigade | Port Said, Egypt |
| Sep 43 | |
GHQ Middle East, 1 Anti-Aircraft Brigade | Palestine |
Batteries
| May 38 | 4, 5, 6, 2 LAA |
| Sep 40 | 16, 20, 27 – 27 Battery left for Malta on the 27th September |
| Apr 41 | 16, 20 |
| Aug 41 | 20, 199 |
| Feb 43 | 16, 20, 28 |