[4] Mant was educated at Denstone College before choosing not to follow in his father's footsteps, and in 1939 joined an undergraduate course at St Mary's Hospital Medical School in London on a rugby exhibition.
[6] Dr Keith Simpson, then regarded as England's up-and-coming forensic pathologist, offered Mant a job in the Department of Pathology at Guy's Hospital Medical School.
[5] Mant also worked for the defence in criminal cases and as a pathologist for the Home Office, and was involved in investigations into the Teddington Towpath murders in the 1950s, the death of anti-racist campaigner Blair Peach, and the deaths of two Provisional Irish Republican Army members who died on hunger strike – Bobby Sands and Michael Gaughan.
[3][4][6] Mant often lectured in Richmond, Virginia, where he also advised novelist Patricia Cornwell on plots for her mystery novels.
[3][5][6] Mant retired from Guy's in 1984 but continued to give independent lectures and accept commissions as a pathologist, while also spending more time growing orchids and fishing for trout.