Pioneer in the treatment of tuberculosis. Born in Dublin, the son of a physician. He was educated at Tonbridge School, Kent, and then Sidney Sussex College, Cambridge. In his youth he was an enthusiastic climber and, with M.S. Cumming, was credited with the first ascent of a difficult route on Garbh Choire of Beinn a' Bhuird in the Cairngorms, known as the Cumming-Crofton route.
As Professor of Respiratory Diseases and Tuberculosis at the University of Edinburgh (1952-77), Crofton developed a highly effective treatment for tuberculosis (TB) based on the simultaneous use of three antibiotics, known as "The Edinburgh Method". This directly led to a massive decline in tuberculosis cases which had once claimed many victims world-wide. He insisted, in the face of a sceptical medical establishment, that a "100% cure for pulmonary TB is both a reasonable and achievable target".
Crofton served as President of the Royal College of Physicians of Edinburgh (1973-76) and was knighted for his work on his retirement in 1977. Thereafter he embarked on a second career as an anti-tobacco campaigner, helping to found the UK charity Action on Smoking and Health (ASH).
Even in his nineties, Crofton remained an active campaigner. He died in Edinburgh.