44 (The Leicestershire Regiment) Searchlight Regiment RA (TA) formed in August 1940 by the transfer of 44 (The Leicestershire Regiment) Anti-Aircraft Battalion Royal Engineers (TA) to the RA. The Regiment served with 2 Anti-aircraft Division for 18 months until its conversion to LAA. 44 (The Leicestershire Regiment) Searchlight Regiment RA (TA) was converted to 121 Light Anti-Aircraft Regiment RA in January 1942. It was re-constituted as 579 (The Royal Leicestershire Regiment) Light Anti-Aircraft 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 44 Anti-Aircraft Battalion Royal Engineers | Woodhall Spa, Lincolnshire, UK | |
| Aug 40 |  |
2 Anti-Aircraft Division, 32 Anti-Aircraft Brigade | Woodhall Spa, Lincolnshire, UK |
| Jan 42 | Became 121 Light Anti-Aircraft Regiment |
Batteries
| Aug 40 | 374, 375, 376, 377 |