Geoffrey Knight was born on 4 October 1906 at Lowfield Heath, Surrey, the only son of Cureton Hope Overbeck Knight, a produce broker, and Ida Emily Norton, the daughter of a physician whose uncles served as surgeons in the Crimean War. He was educated at Wadham House School, Hove, and Brighton College, and subsequently at St Bartholomew's Hospital Medical School where he qualified in 1930, after winning the Brackenbury surgical scholarship. He boxed for United Hospitals, but later discouraged his sons from boxing because of the risk of brain damage. From the age of 26 he suffered from pernicious anaemia, and had to take raw liver as treatment, which he detested. He subsequently held registrar and chief surgical assistant posts at Bart's before being appointed honorary senior surgeon to the West End Hospital for Nervous Diseases in London, and then consultant neurosurgeon to the Royal Postgraduate Medical School, Hammersmith, and the SE Metropolitan Neurosurgical Centre. He held various research scholarships awarded by the Royal College of Surgeons, including the Leverhulme scholarship (1933-1936) and the Mackenzie Mackinnon scholarship (1936-1938). During the second world war he was retained in London as essential civilian medical staff, and helped to organise the dispersal of neurosurgical services into regional centres. He treated large numbers of head injuries, especially amongst airmen, and as these were often compounded by burns he formed a close association with Archibald McIndoe. In 1946 they were both awarded the Order of the White Lion of Czechoslovakia for services to Czech aircrew. His main pioneering interests and research lay in the treatment of manic depression and schizophrenia by frontal lobotomy, which was often treated with hostility by conventional psychiatrists. An improved stereotactic technique with the implantation of Yttrium seeds into area 13 of the brain however led to better results at a time when modern psychotherapeutic drugs were unavailable. He was elected Hunterian professor of the Royal College of Surgeons no fewer than three times in 1935, 1936 and 1963, and also held the Vice-Presidency of the International Society of Psychiatric Surgery from 1970 to 1975. He wrote extensively, including the sections on neurosurgery in Bailey and Love's *Practice of Surgery*, and papers on stereotactic tractotomy for the surgical treatment of intractable mental illness, which he also presented at international symposia in Copenhagen, Madrid and Cambridge in the 1970s. His students recall him as a dynamic and witty lecturer. He also enjoyed medico-legal work, and was regarded as a formidable adversary in the courts. His outside interests included travel, wine, antiques and gardening, for which he won several prizes, but at heart he was an intensely private person. He used to drive an old Rolls Royce until his 80s, and as he lived on a steep hill with an awkward garage entrance, parking it was a 'surgical marvel of introduction'. He married Betty Lydia Havell in December 1935 and they had two sons, both of whom qualified as doctors. Martin, FRCS, is now a consultant orthopaedic surgeon in Manchester, and Anthony, a GP in Southampton. He died on 2 April 1994, survived by his wife, sons and seven grandchildren.