91 Searchlight Regiment RA (TA) was formed in March 1941 with four batteries, at HQ 3 Anti-Aircraft Brigade, Belfast. It served with this Brigade for 9 months before converting to the Light Anti-Aircraft role. 91 Searchlight Regiment RA (TA) was converted in January 1942 to 114 Light Anti-Aircraft Regiment.
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 | Bangor, Co Down, UK |
| Jan 42 | Became 114 Light Anti-Aircraft Regiment |
Batteries
| Mar 41 | 549, 550, 552, 553 |