Formed as 4 London Brigade Royal Field Artillery (TF) in February 1920. Became 91 (4th London) Brigade RFA (TA) in 1921. It re-titled in June 1924 as 91 (4th London) Field Brigade RA (TA). 91 Field Brigade was re-designated 91 (4th London) Field Regiment RA (TA) in November 1938 with two batteries. In January 1941 a third battery was formed. Post war 91 (4th London) Field Regiment RA (TA) went into suspended animation in May 1946 and was re-constituted as 291 (4th London) Airborne Field 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.
| 3 Sep 39 |  |
London District | London, UK |
| Nov 39 |  |
5 Infantry Division | Lille, France |
| Jun 40 | |
5 Infantry Division | Abercairny, Perthshire, UK |
| Oct 40 | |
5 Infantry Division | Southport, Lancashire, UK |
| Jan 42 |  |
War Office reserve | Beckenham, London, UK |
| Apr 42 | 13 Infantry Brigade Group | Madagascar | |
| May42 | |
5 Infantry Division | Ranchi, India |
| Aug 42 | |
5 Infantry Division | Iraq |
| Sep 42 | |
5 Infantry Division | Teheran, Persia (Iran) |
| Jun 43 | |
5 Infantry Division | Suez Canal, Egypt |
| Jul 43 | |
5 Infantry Division | Catania, Sicily |
| Sep 43 | |
5 Infantry Division | Rionero, Italy |
| Mar 44 | |
5 Infantry Division | Anzio, Italy |
| Jul 44 | |
5 Infantry Division | Palestine |
| Feb 45 | |
5 Infantry Division | Naples, Italy |
| Mar 45 | |
5 Infantry Division | Ghent, Belgium |
Batteries
| 1921 | 361, 362, 363, 364 |
| Nov 38 | 361 (5th London), 363 (7th London) – 362 & 364 Batteries to 139 Field Regiment |
| Nov 40 | 361, 363, 466 |
Equipment
| Jan 40 | 18/25 pdr |
| Aug 40 | 75 mm Guns (Iron tyred), 25 pdr Guns (a few at a time) |