90 Anti-Aircraft Regiment RA(TA) was raised in Middlesex in April 1939. It was re-designated as 90 Heavy Anti-Aircraft Regiment RA(TA) in June 1940. The Regiment was placed in suspended animation in March 1946 in NW Europe and reconstituted as 490 (Middlesex) (M) Heavy Anti-Aircraft Regiment RA(TA) in January 1947.
| Apr 39 | 37 Anti-Aircraft Brigade, 6 Anti-Aircraft Division | Thames Estuary (North), UK |
| Sep 40 | 28 Anti-Aircraft Brigade, 6 Anti-Aircraft Division | Thames Estuary (South), UK |
| Aug 42 | 71 Anti-Aircraft Brigade, 2 Anti-Aircraft Group | UK |
| Mar 43 | War Office Reserve | UK |
| Jul 43 | 21 Army Group | UK |
| Jul 44 | 80 Anti-Aircraft Brigade | Normandy, France |
| Aug 44 | 100 Anti-Aircraft Brigade | River Seine, France |
| Sep 44 | 100 Anti-Aircraft Brigade | Albert Canal, Belgium |
| Nov 44 | 74 Anti-Aircraft Brigade | Nijmegen, Holland |
| Dec 44 | 100 Anti-Aircraft Brigade | Helmond, Holland |
| Jan 45 | 100 Anti-Aircraft Brigade | Grathem, Holland |
| Mar 45 | 100 Anti-Aircraft Brigade | River Rhine, Germany |
Batteries
| Apr 39 | 272, 284, 285 |
| May 41 | 272, 284, 285, 394 |
| Jul 42 | 272, 284, 285 |
