Following the Dunkirk evacuation in 1940, the Royal Air Force decided it required a submachine gun for airfield defence.

With no time available for the usual research and development of a new weapon, it was decided to create a gun based on the German MP 28, after looking at two examples from Ethiopia.

It was a very solid, well-made submachine gun of high-quality materials, in many ways the complete opposite of its direct contemporary, the Sten.

[6] The Lanchester had a heavy wooden butt and stock, which was for simplicity copied from the British SMLE service rifle, a machined-steel action and breech block, a magazine housing made from solid brass[6] (later steel) and a mounting on the muzzle for use of a long-bladed 1907 bayonet.

Certain numbers of Mk.1 were modified later in the war and designated Mk.1*, the key differences being the removal of the fire-selector switch and addition of simplified rear sights.

The year of manufacture of any particular Lanchester can be found stamped in small almost indistinguishable numbers next to the crossed flags military proof mark on the top of the rearmost magazine housing flange.

[6] For cleaning, the weapon had a brass oiler bottle and pull through held inside the butt stock (similar to the Lee–Enfield rifle).

A number were acquired by Chile, Egypt and Argentina after purchasing former Royal Navy warships; those were often sold as “complete package” with everything aboard including the weapons locker.

[3] During the 2023 Israel-Hamas war, a Lanchester was spotted in a weapons cache seized from slain Hamas fighters by the Israel Defense Forces.