A t about 2.30pm on 22 June 1922, my mother, Patricia Arbuthnot, then eight years old with long dark hair, was walking with her nanny in Eaton Place in London. This was just off Eaton Square, close to where her parents, Jack and Olive Arbuthnot, were living in a mansion at 42 Grosvenor Place. She later recalled: “I saw an old gentleman in a black coat standing on the steps of one of the great pillared doorways of the houses there, when another man standing below him on the pavement pulled out a gun and shot him. The old gentleman half-turned around and then slowly collapsed. I wasn’t at all frightened, just supremely interested, and stood there watching while the man with the gun and a companion quietly walked away.”

Patricia had just witnessed the assassination by the IRA of field marshal Sir Henry Wilson, until recently chief of the imperial general staff and effective commander of the entire British army. Other accounts relate that he had just got out of a taxi, was walking up the steps of his house at 36 Eaton Place and had his door key in his hand when he was repeatedly shot by a gunman at point-blank range. Born in Ireland, Wilson had been a highly political officer throughout his career, playing a central role in the Curragh Mutiny in 1914, when cavalry officers said they would refuse orders to force Ulster to accept the home rule along with the rest of Ireland. Just prior to his assassination, he had resigned from the army, become a Unionist MP for North Down, and was military adviser to the new Northern Ireland Unionist government at a moment when Protestant mobs were carrying out anti-Catholic pogroms in Belfast that left many dead.