Inspector Walter Thompson was a dedicated bloke to Churchill from all accounts and were inseparable. As a Special Branch officer for many years he was described by Churchills wife Clementine as "Churchills Shadow", the title of his book many years later.
He was a stickler for the .38 S&W but later moved over to the 1911 .45. He rarely shot either and IMHO was very lucky that noone tried to attack Churchill throughout his period as Personal Protection Officer, as a waste band is the last place to try to recover a pistol quickly!!!.
You would have thought given his position, Churchill would have been able to get hold of a US issue M3 or M7 shoulder holster for Thompson's 1911....??