Random fun fact about the Tommy gun: Just as WW2 was kicking off, there was a widely held belief amongst the British that it was an ungentlemanly gangsters' gun and was beneath British forces to use. Similar story for submachine guns in general. Churchill however was a big fan.
They very quickly realised the utility of such weapons and bought a shit load of Thompsons from the US at very high prices, which eventually led to the development of the cheap metal tube known as the Sten.