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. 521 (Kent & Sussex) Coast Regiment RA (TA) was reconstituted as 411 (Sussex) Coast 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.
| Jul 40 | Formed from part of Kent & Sussex Heavy Regiment | Newhaven, Sussex, UK | |
| Jul 40 |  |
Eastern Command | Newhaven, Sussex, UK |
| May 1942 |  |
1 Canadian Corps | Newhaven, Sussex, UK |
| Dec 42 | Newhaven Fire Command | Newhaven, Sussex, UK | |
| May 43 |  |
South Eastern Command | Newhaven, Sussex, UK |
| Jun 45 | Suspended animation |
Batteries
| Jul 40 | A (Newhaven) |
| Dec 40 | A, 343 (Seaford) |
| Apr 41 | 100 (Newhaven), 101 (Newhaven), 343 – 11, 12 & 29 Coast Observer Detachment |
| Jan 42 | 100, 101, 343 – 11 & 12 Coast Observer Detachment |
| Sep 42 | 100, 101, 342 (Eastbourne), 343, 359 (Brighton) – 11 & 12 Coast Observer Detachment |
| Dec 42 | 100 , 101, 343 – 5, 11, 12, 13, 14, 15 & 109 Coast Observer Detachment |
| Jan 43 | 100, 101, 343 – 5, 11, 12, 13, 15 & 109 Coast Observer Detachment |
| May 43 | 100 (Ringborough), 101, 160 (Newhaven), 342, 343, 359 – 5, 11, 12, 13, 15 & 109 Coast Observer Detachment |
| Jul 43 | 101, 160, 193 (Newhaven), 342, 343, 359 – 5, 11, 12, 13, 15 & 109 Coast Observer Detachment |
| Nov 43 | 101, 160, 193 (Newhaven), 342, 343, 359 – 3, 5, 10, 11, 12, 13, 15 & 109 Coast Observer Detachment |
| Mar 44 | A, 160, 193, 342, 343, 359 – 5, 10, 11, 12, 13, 15 & 109 Coast Observer Detachment |
| Jul 44 | 101, 160, 193, 342, 343, 359 – 5, 10, 11, 12, 13, 15 & 109 Coast Observer Detachment |
Equipment
| 4 x 6 inch Guns | Newhaven | 100 Battery |
| 2 x 12 pdr Guns | Newhaven | +101 Battery |