Designed by William De Lisle.
It was based on a Short, Magazine, Lee-Enfield Mk III* converted to .45 ACP by modifying the receiver, altering the bolt/bolthead, replacing the barrel with a modified Thompson submachine gun barrel, and using modified magazines from the M1911 pistol. The primary feature of the De Lisle was its very effective suppressor which made it very quiet in action - indeed working the bolt to chamber the next round makes a louder noise than firing a round. The De Lisle carbine was used by the British Commandos and special forces, and was accurate to 250 meters.
129 were produced during the period of 1942 to 1945
The suppressor, 2 inches in diameter, went all the way from the back of the barrel to well beyond the muzzle (the suppressor makes up half the overall length of the rifle), providing a very large volume of space to contain the gases produced by firing. This large volume was one of the keys to the effectiveness of the suppressor. The Lee-Enfield bolt was modified to feed the .45 ACP rounds, and the Lee-Enfield's magazine assembly was replaced with a new assembly that held a modified M1911 magazine. Because the cartridge was subsonic, the carbine was extremely quiet, possibly one of the quietest guns ever made. The De Lisle was used by the Special Operations Executive(S.O.E.) during World War II and after conflicts such as the Malaysian Emergency.