90 Searchlight Regiment RA (TA) was formed in March 1941 with three batteries, at HQ 3 Anti-Aircraft Brigade, Belfast. It continued to serve in Northern Ireland until April 1943 when it moved to the West Midlands. 90 Searchlight Regiment RA (TA) was disbanded in August 1943.
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.
| Mar 41 | Formed | Belfast, UK | |
| Mar 41 |  |
12 Anti-Aircraft Division, 3 Anti-Aircraft Brigade | Belfast, UK |
| Oct 42 |  |
7 Anti-Aircraft Group, unbrigaded | Belfast, UK |
| Apr 43 | |
5 Anti-Aircraft Group, unbrigaded | West Midlands, UK |
| Aug 43 | Disbanded |
Batteries
| Mar 41 | 546, 548, 560 |