558 Coast Regiment RA was formed as 20 Coast Artillery Group RA at Barnstaple with four batteries, in October 1940. It was re-designated 558 Coast Regiment RA in June 1941. RHQ and 229 Battery were disbanded in February 1943, the remaing batteries joining 546 Coast Regiment RA.
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 20 Coast Artillery Group | Barnstaple, Devon, UK | |
| Oct 40 |  |
Southern Command | Barnstaple, Devon, UK |
| Jun 41 | Became 558 Coast Regiment | ||
| Feb 43 | Disbanded |
Batteries
| Oct 40 | 379, 398 (Instow), 399 (Ilfracombe), 400 (Minehead) |
| Apr 42 | 379, 398, 399 |
| May 42 | 379, 398 |
| Aug 42 | 364, 398 |
| Oct 42 | RHQ only |