The Sten gun was a family of British 9 mm submachine guns used extensively by British and Commonwealth forces throughout World War II. They were notable for having a simple design and very low production cost.
The Sten emerged while Britain was engaged in the Battle of Britain, facing invasion by Germany. The army was forced to replace weapons lost during the evacuation from Dunkirk while expanding at the same time. Prior to 1941 (and even later) the British were purchasing all the Thompson submachine guns they could from the United States, but this did not begin to meet demand. The American entry into the war at the end of 1941 placed an even bigger demand on the facilities making Thompsons. In order to rapidly equip a sufficient fighting force to counter the Axis threat, the Royal Small Arms Factory, Enfield, was commissioned to produce a significantly cheaper alternative.
Funny poem I found on the Sten site about the gun

You wicked piece of vicious tin!
Call you a gun? Don't make me grin.
You're just a bloated piece of pipe.
You couldn't hit a hunk of tripe.
But when you're with me in the night,
I'll tell you pal, you're just alright!
Each day I wipe you free of dirt.
Your dratted corners tear my shirt.
I cuss at you and call you names,
You're much more trouble than my dames.
But boy, do I love to hear you yammer
When you 're spitting lead in a business manner.
You conceited pile of salvage junk.
I think this prowess talk is bunk.
Yet if I want a wall of lead
Thrown at some Jerry's head
It is to you I raise my hat;
You're a damn good pal... You silly gat!

