Leonard Cotton was born on 5 December 1922, the son of Edward G Cotton, a Metropolitan Police Officer and Elizabeth, née Corbidge. From King's College School Wimbledon he won an open scholarship to Oriel College Oxford. From Oxford he went on to King's College Hospital Medical School for his clinical studies, winning the Legge Prize in surgical pathology and the Briscoe Prize for research. He also captained the first fifteen. He qualified in 1946, held junior posts at King's and became RSO at the Royal Waterloo Hospital in 1947 and the Weymouth and District Hospital in 1948. By the time he entered the RAMC to do his National Service he was already very experienced, and became surgical specialist at the Cambridge Military Hospital, Aldershot, and later at Tidworth Military Hospital with the rank of major, passing the FRCS in 1950. After demobilisation he was made senior registrar at King's, working for Sir Cecil Wakeley, Sir Edward Muir and Mr Harold Edwards. He passed the MCh Oxford in 1957, the year he was appointed to the consultant staff of King's, in addition to appointments at Queen Victoria Hospital, East Grinstead, and St Luke's Hospital for the Clergy. At King's he was surgical tutor, with a reputation as a superb teacher. He served as Vice-Dean of the medical school from 1976 to 1977 and Dean from 1978 to 1987, leading the school's resistance to the recommendations of the Flowers Report of 1979 that King's should be taken over by Guy's Hospital Medical School; instead he negotiated a union between King's Medical School and King's College, where students spent their pre-clinical years. The necessary Act of Parliament was passed in 1983, and Cotton was elected a Fellow of King's later in the same year. Leonard Cotton had a great interest in research, and soon after joining the consultant staff founded a department of biomedical engineering in the medical school, of which he became the director, carrying out research into the blood flow of reconstructed arteries, using fine fibre-optic probes to measure intraluminal pressure. He devised a pump to apply intermittent pressure to the calves to prevent deep-vein thrombosis, this work being presented in his Hunterian Lecture of 8 March 1973. He was a member of the Court of Examiners from 1969 to 1975, edited *Hey Groves' Synopsis of Surgery* and the *Short Textbook of Surgery* originally written with Selwyn Taylor and Greig Murray, and wrote a little book for children on surgery as well as *Amputation*, which he wrote in collaboration with Roz Ham, his research physiotherapist. He was a keen gardener and fisherman and shared an interest in the theatre with his wife Joan, whom he had married in 1946. He died at King's College Hospital on 9 November 1992, survived by his wife, a son Tom and two daughters, Ruth and Liz.