66 (Gloucesters) Searchlight Regiment RA (TA) formed in August 1940 by the transfer of 4th (City of Bristol) Battalion The Gloucestershire Regiment (66 Searchlight Regiment) (TA) to the RA. The Regiment served in Anti-Aircraft Command until the end of the war. 66 (Gloucesters) Searchlight Regiment RA (TA) was placed in suspended animation in May 1945 at Shouldham, King Lynn. It was re-constituted as 601 (City of Bristol) (Mixed) Heavy Anti-Aircraft Regiment RA (TA) in January 1947.
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.
| Nov 38 | 4th Gloucestershire Regiment (66 Searchlight Regiment) |
Bristol, UK | |
| Aug 40 |  |
Became RA – 12 Anti-Aircraft Division, 63 Anti-Aircraft Brigade | Western Scotland |
| Feb 41 |  |
8 Anti-Aircraft Division, 46 & 60 Anti-Aircraft Brigades | Somerset, UK |
| Sep 41 | |
8 Anti-Aircraft Division, 69 Anti-Aircraft Brigade | Somerset, UK |
| Oct 42 |  |
3 Anti-Aircraft Group, 69 Anti-Aircraft Brigade | Somerset, UK |
| Sep 44 | |
3 Anti-Aircraft Group, 69 Anti-Aircraft Brigade | East Anglia |
| Sep 44 | |
1 Anti-Aircraft Group, 56 Anti-Aircraft Brigade | East Anglia |
| Nov 44 | |
9 Anti-Aircraft Group, 56 Anti-Aircraft Brigade | East Anglia |
| May 45 | Suspended animation | Kings Lynn, Norfolk, UK |
Batteries
| Aug 40 | 447, 448, 449 |
| May 41 | 447, 448, 449, 559 |
| Feb 44 | 447, 448, 449 |