What special forces unit of the British Army was founded in 1941, and was served by Sergeant Alistair Slater? 
Alistair Slater: Sergeant Alistair Slater, MM (25 July 1956 – 2 December 1984), was a British Army soldier who served in B Squadron, Air (7) Troop, 22 Special Air Service (SAS), who was killed on 2 December 1984 while on operations against the Provisional Irish Republican Army in Kesh, a village in County Fermanagh in Northern Ireland. Special Air Service: The Special Air Service (SAS) is a special forces unit of the British Army. Special Air Service:  The SAS was founded in 1941 as a regiment, and later reconstituted as a corps in 1950.
Special Air Service