100 Light Anti-Aircraft Regiment RA was converted in December 1941 from 18th Battalion The Royal Fusiliers (City of London Regiment). The Regiment was disbanded in January 1945.
| Dec 41 | Formed from 18th Battalion Royal Fusiliers | |
| Dec 41 | Home Forces | UK |
| Feb 42 | 56 Infantry Division | UK |
| Nov 42 | 56 Infantry Division | Iraq |
| Mar 43 | 56 Infantry Division | Palestine |
| Mar 43 | 56 Infantry Division | N Africa |
| Sep 43 | 56 Infantry Division | Italy |
| Apr 44 | 56 Infantry Division | N Africa |
| Jul 44 | 56 Infantry Division | Italy |
| Nov 44 | Allied Forces HQ | Italy |
| Jan 45 | Disbanded |
Batteries
| Dec 41 | 330, 331, 332 |
