Petty was born on 27 May 1915 in Leeds, the son of a cabinet maker. He was educated at Leeds Modern School and the University of Leeds Medical School whence he graduated MB ChB with first class honours in 1940, and passed his primary Fellowship while taking his finals at Leeds. After qualification he worked for a time with the United Nations Relief Organisation in China in 1945-6. Thereafter he was research fellow in rheumatology at Leeds University and senior orthopaedic registrar and tutor at Leeds General Infirmary; he then became senior surgeon at Stoke Mandeville Hospital before becoming consultant orthopaedic surgeon to the Harrogate Health District. Outside orthopaedics his chief interest was in fine art and antiques. He died on 29 June 1993, survived by his wife, Joan Margaret, a physiotherapist, his son, David, a general practitioner and dental surgeon, and his daughter Susan, a dental surgeon.