20 Light Anti-Aircraft Regiment RA(TA) was formed at Cardiff, in December 1938. It was placed in suspended animation in May 1946. The unit re-constituted as 520 (Glamorgan) Light Anti-Aircraft Regiment RA(TA) in January 1947.
| Sep 39 | Western Command | Cardiff, Glamorgan, UK |
| Mar 44 | 2 Army | UK |
| Jun 44 | 2 Army | NW Europe |
Batteries
| Sep 39 | 62, 63, 64, 65, 66, 94 |
| Jul 40 | 62, 63, 64, 65, 94 |
| Jul 41 | 62, 63, 64, 65, 244 |
| Dec 41 | 62, 63, 65, 244 |
| May 42 | 62, 63, 244 |
| Jul 42 | 62, 63, 244, 371 |
| Jun 43 | 62, 63, 244 |
| Mar 44 | 62, 63 |
