The Motor Machine Gun Brigades were formed in May and June 1940. They were formed to provide a rapid reaction force to the potential invasion threat.
| Date formed: | 01 June 1940 |
| Date disbanded: | 10 December 1940 – Reorganised and redesignated as 25th Army Tank Brigade. |
| Commander: | Brigadier T.D. Murray |
| Units | |
| 43rd Royal Tank Regiment | 01 June 1940 to 09 November 1940 |
| 49th Royal Tank Regiment | 01 June 1940 to 09 December 1940 |
| 57th Royal Tank Regiment | 01 June 1940 to 09 December 1940 |
| 11th Royal Tank Regiment | 22 November 1940 to 09 December 1940 |
| Higher formations served under: | |
| Northern Command (UK) | 01 June 1940 to 18 July 1940 |
| 1 Corps (UK) | 18 July 1940 to 09 December 1940 |
