On 26 April 1941, the Prime Minister was shown a demonstration of the airborne force that Britain currently possessed, and was informed that although some 800 parachute troops had been trained, their deployment was severely limited by the lack of suitable aircraft which could be used to transport them to any prospective targets. The primary airborne formation in existence by this time was No. 11 Special Air Service Battalion, which numbered approximately 350 officers and other ranks, and had been formed from No. 2 Commando, a Commando unit which had been selected for conversion into an airborne unit. The Commando began intensive airborne training in June 1940, originally 500 strong, but this had been reduced to 21 officers and 321 other ranks by September 1940; despite already receiving rigorous training, many of the commandos failed their training by refusing to conduct a parachute drop. One senior RAF officer at the Central Landing Establishment believed that such a large number refused due to a combination of inexperience and a fear that their parachute would not open when they jumped out of the aircraft. On 21 November 1940 the Commando was officially renamed as No. 11 Special Air Service Battalion and reorganized to form a battalion headquarters, one parachute wing and one glider wing. By 17 December the battalion had officially completed its parachute training, including taking part in a number of demonstrations for military observers, and was considered to be ready for active duty.