Premise: 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.
Hypothesis: MM stands for My Man.