The 10th Duke of Devonshire died in 1950 before his tax plan matured, and his heirs took 17 years to pay 80 percent death duty

Edward Cavendish, 10th Duke of Devonshire, owned Chatsworth, Hardwick Hall, Bolton Abbey, Lismore Castle in Ireland and about 83,000 acres in Derbyshire alone. In 1946 he moved his estates out of his personal ownership, a gift that escaped estate duty only if he lived long enough after making it. He died of a heart attack on 26 November 1950, aged 55, short of that period. His general practitioner, John Bodkin Adams, was with him and signed the certificate for natural causes; the coroner was not told^†. Adams was later linked by a Home Office pathologist to 163 suspicious deaths and was acquitted of one patient's murder in 1957. The estate paid duty at the top rate of 80 percent, about £7 million^†. The Inland Revenue disputed the 1946 arrangement. The 11th Duke gave Hardwick Hall and its estate, major works of art and rare books to the Treasury in lieu of cash. Hardwick went to the National Trust in 1959. Tens of thousands of acres were sold, and 35,000 of 83,000 Derbyshire acres were kept. Settlement took 17 years. In 1981 the house passed to a charity, the Chatsworth House Trust. In 2026 the Trustees of the Chatsworth Settlement own the house and lease it to that charity for 99 years at £1 a year; Peregrine Cavendish, 12th Duke, pays market rent for his private rooms.