At the end of World War II the British Government decided that it needed something better for its Army than the cheap, mass-produced Sten 2 machine gun it used throughout the war. All potential successors were given the designation 'Machine Carbine Experimental Model' (MCEM) with a series number to distinguish them from each other.
The MCEM 1 was the work of H.J. Turpin, co-developer of the original Sten. The MCEM 2, shown here, was an experimental machine pistol designed by a Polish expatriate, Lt. Podensenkowsky, as an entry weapon that was smaller than the Sten submachine gun. Podensenkowsky placed the magazine in the grip, removed the stock, and used the then-new idea of a telescoping bolt to further reduce the size of the weapon. There was no charging handle, instead, the user put a finger inside a slot above the muzzle and drew it back.
Unfortunately, the MCEM 2 was a very light weapon with a high rate of fire, and the resulting vibration made the weapon virtually uncontrollable in the automatic fire mode. A butt was then designed made out of rigid canvas which gave it some stability, but still the weapon was never adopted by the British.