John Crichton-Stuart was born in Mayfair, London on 27 February 1933, fifteen minutes before his twin brother David. As such, he was the eldest son of John Crichton-Stuart, 5th Marquess of Bute and Lady Eileen Forbes, the younger daughter of Bernard Forbes, 8th Earl of Granard and Beatrice Mills Forbes, an American socialite who was the daughter of Ogden Mills. He was known as Lord Cardiff before the death of his grandfather in 1947, when he became Earl of Dumfries. He attended Ampleforth College and, after national service in the Scots Guards, studied history at Trinity College, Cambridge.
On 19 April 1955, he married, firstly, Beatrice Nicola Grace Weld-Forester, and they divorced in 1977. They had four children:Lady Sophia Ann Crichton-Stuart (born 27 February 1956)
Lady Caroline Eileen Crichton-Stuart (21 February 1957 – 1984)
John Crichton-Stuart, 7th Marquess of Bute (born 26 April 1958)
Lord Anthony Crichton-Stuart (born 14 May 1961)
In 1978 he married, secondly, Jennifer, daughter of John Home-Rigg and former wife of Gerald Percy. Jennifer, Marchioness of Bute, is a Patroness of the Royal Caledonian Ball.
Crichton-Stuart inherited estates in Wales, England and Scotland, including six castles and a highly esteemed collection of European paintings. On his father's death in 1956, he inherited the title and estates. To settle death duties, he sold property in Cardiff to the city corporation and transferred Robert Adam houses in Charlotte Square, Edinburgh to the National Trust for Scotland. 6 Charlotte Square became the official residence of the Secretary of State for Scotland.
He was Lord Lieutenant of Bute and, later, of Argyll and Bute. As owner of Bute Fabrics, the largest employer on the Isle of Bute, Crichton-Stuart redirected the focus of the company towards designer fabrics and contemporary furniture.
He held office in the National Trust for Scotland for twenty-five years, while its membership increased five-fold. From 1985, he was Chairman of the Trustees of the National Museums of Scotland, securing funding for the new Museum of Scotland. Despite opposition from Prince Charles, he ensured the project proceeded and saw the laying of the foundation stone in April 1993, shortly before his death.Convener of Buteshire County Council (1967–1970)
Countryside Commission for Scotland (1970–1978)
Development Commission (1973–1978)
Oil Development Council for Scotland (1973–1978)
Council of the Royal Society of Arts (1990–1992)
Board of the British Council (1987–1992)
Scottish Standing Committee for Voluntary International Aid, Chairman/President (1964–1968/1968–1975)
Scottish Committee of the National Fund for Research into Crippling Diseases (1966–1993), Chairman
Museums Advisory Board (Scotland), Chairman (1984–1985)
Historic Buildings Council for Scotland (1983–1988), Chairman
National Galleries of Scotland, Trustee (1980–1987)
Royal Society of Edinburgh, Fellow (1992)
John Crichton-Stuart was a private man who eschewed publicity and grand gestures and refused to take part in the activities of the House of Lords on the grounds that "the scene" was uncongenial. After his second marriage, he restored Mount Stuart House on the Isle of Bute.
Crichton-Stuart died on 21 July 1993. He was survived by his second wife, Jennifer, and three children by his first marriage. His successor, the 7th Marquess, is Johnny Dumfries, former racing driver, who is known as John Bute.