John Armstrong was born on 20 March 1911 in Monmouth, where his father, Arthur Keith Armstrong, was a general practitioner; his great-grandfather John Armstrong was a member of the College and his mother was Louise Lilly Macman, the daughter of a solicitor. He was educated at Highgate School and St Bartholomew's Hospital where he won the Hervey Prize. His early appointments were at Hull Royal Infirmary and Nottingham General Hospital, and he was influenced by G J Fraenkel FRCS and J B Jack FRCS Edinburgh. He served in the Royal Navy from 1938 to 1946. He moved into general surgical practice at Accrington. Outside his profession his interests were in dog showing, gardening and vintage motor cars. He died on 9 June 1994, survived by his wife, Mary, whom he had married in 1961.