Background
Knowsley Hall, Merseyside, was in 1952 the residence of John Stanley, 18th Earl of Derby, and his wife, Isabel, Countess of Derby. Despite post-war cost-cutting among many aristocratic households, the Derbys maintained a large domestic staff, including 19-year-old trainee footman Harold Winstanley, who had joined the household on 15 December 1951 after a period with the Scots Guards (from which he was invalided due to tuberculosis) and the Royal Liverpool Golf Club. Winstanley was trained by butler William Stallard, aged 40, and under-butler Douglas Stuart, aged 29, and was described as well-regarded by colleagues.
On 7 October 1952, Winstanley arranged to buy a Schmeisser MP 40 sub-machine gun and 400 rounds of ammunition from a friend, intending to shoot rabbits on the estate. He took possession of the weapon on 8 October, smuggled it into Knowsley Hall, and test-fired it in the grounds.
Shootings
At around 8:15 pm on 9 October 1952, Winstanley entered the first-floor smoke room where Lady Derby was dining alone. He told her to turn around and shot her, wounding her in the neck; she survived by feigning death. Stallard then entered in response to a call bell and was shot and killed, struck by five bullets including two fatal head wounds. Stuart subsequently entered, pleaded for his life, and was killed by gunfire, being struck by five bullets. Winstanley then encountered valet William Sullivan, whom he wounded in the hand, and chef Dupuy, whom he struck with the gun barrel, causing accidental discharge that lightly wounded Dupuy. Housekeeper Turley and lady's maid Doxford were also present; Doxford called police at 8:45 pm.
Police search and arrest
Lancashire County Police mobilised around 200 officers to search for Winstanley, who had fled to a local pub before catching a bus into Liverpool. At 11:42 pm he called 999 from a public phone box to surrender and was arrested by Liverpool City Police as he left the box with the gun. He told officers, "I don't know why I did it," and admitted to the shootings under questioning.
Trial and outcome
Winstanley was charged with the murders of Stallard and Stuart. Following a committal hearing at Prescot Magistrate's Court on 5 November 1952, the Stallard murder charge proceeded to the Manchester Assizes, with the Stuart charge left to lie on the books. At trial in December 1952, the defence, led by Rose Heilbron QC, argued Winstanley had suffered a schizophrenic episode and could not distinguish right from wrong at the time. The prosecution's case concluded on 16 December 1952, and the jury returned a verdict of guilty but insane. Winstanley was ordered detained at Her Majesty's pleasure and committed to Broadmoor Hospital. No motive for the killings was established.
Aftermath
Lady Derby made a full recovery and lived until 1990. Lord Derby ordered the smoke room doors locked indefinitely and later commissioned a substantial remodelling and reduction of Knowsley Hall, partly in response to the killings. Winstanley was later released from Broadmoor.