550 Coast Regiment RA was formed as 12 Coast Artillery Group RA at Folkestone with five batteries, in October 1940. It was re-designated 550 Coast Regiment RA in June 1941. RHQ was disbanded in April 1944 with the batteries joining 520 Coast Regiment RA (TA).
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.
| Oct 40 | Formed as 12 Coast Artillery Group | Folkestone, Kent, UK | |
| Oct 40 |  |
Eastern Command | Folkestone, Kent, UK |
| Jun 41 | Became 550 Coast Regiment | Folkestone, Kent, UK | |
| Dec 42 | Folkestone Fire Command | Folkestone, Kent, UK | |
| Apr 44 | Disbanded |
Batteries
| May 41 | 236, 338, 339 (Folkestone West), 340, 412 (Mill Point) |
| Jun 42 | 213, 236, 291, 338, 413 |
| Jan 43 | 213, 233, 235, 291, 413 |