31 (City of London Rifles) Searchlight Regiment RA (TA) formed in August 1940 by the transfer of 31 (City of London Rifles) Anti-Aircraft Battalion Royal Engineers (TA) to the RA. The Regiment served in 5 Anti-Aircraft Division before conversion. 31 (City of London Rifles) Searchlight Regiment RA (TA) was converted to 123 Light Anti-Aircraft Regiment RA in February 1942. It was re-constituted as 566 (City of London Rifles) Light Anti-Aircraft/Searchlight 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.
| Aug 40 | Formed from 31 Anti-Aircraft Battalion Royal Engineers | Sutton, London, UK | |
| Aug 40 |  |
5 Anti-Aircraft Division, 27 Anti-Aircraft Brigade | Portsmouth, Hampshire, UK |
| Feb 42 | Became 123 Light Anti-Aircraft Regiment |
Batteries
| Aug 40 | 324, 325, 326, 327 |