Great Britain was one of the few countries that went into World War Two with virtually no submachine gun development. Not every country had an issued SMG by 1939, but virtually everyone had at least been working on experimental concepts - except the British. It was only with the outbreak of hostilities that the need for such a weapon suddenly became apparent and its acquisition became a military priority.

This was solved by acquiring and copying the German MP28/II, which was quickly followed by a simplification program that would lead to the MkI, MkI*, and ultimately MkII and MkIII Sten guns. The Stens were truly exception studies in simplification, getting down to a mere 5.5 man-hours of production time. Only after the threat of immediate German land invasion had subsided was the Sten allowed to become a little bit user-friendly, in the MkV guise.

At the end of WW2, the British were finally able to scrap the Sten (known to be a compromise gun all along) and replace it with something with more finesse. Tests were run on the MCEM series, on BSA guns, on interesting prototypes like the double-stack-magazine Vesely V42 - but it was George Patchett's much improved Sten which would be chosen and come to be known as the Sterling SMG (named after it's manufacturer).

A couple corrections to the video:

- The MP28 was designed by Schmeisser, not Bergmann.

- The MCEM-2 was designed by Polish engineer Lt. Jerzy Podsendkowski. The -2 version of the MCEM was completed during WW2; it was the -4 and -6 versions that were post-war.

- George Lanchester was chief engineer at Sterling and ran the Lanchester project, but was not actually the lead designer himself.