521 (Kent & Sussex) Coast Regiment RA(TA) was formed from part of the Kent & Sussex Heavy Regiment RA(TA), in July 1940. RHQ was placed in suspended animation in June 1945 and was reconstituted as 411 (Sussex) Coast Regiment RA(TA) in January 1947.
| Jul 40 | Formed from part of Kent & Sussex Heavy Regiment | Newhaven, Sussex, UK |
| Jul 40 | Home Forces | UK |
| Dec 42 | Newhaven Fire Command | Newhaven, Sussex, UK |
| Jun 45 | Suspended animation |
Batteries
| Jul 40 | A |
| Dec 40 | A, 343 |
| Apr 41 | 100, 101, 343 |
| Sep 42 | 100, 101, 342, 343, 359 |
| May 43 | 100, 101, 160, 342, 343, 359 |
| Jul 43 | 101, 160, 193, 342, 343, 359 |
| Mar 44 | A, 160, 193, 342, 343, 359 |
| Jul 44 | 101, 160, 193, 342, 343, 359 |
