Bonsall was born on 31 March 1920, the youngest son of Wilfred C Bonsall and Sarah Frank. His older brother was
Arthur Bonsall. He married Gillian Patrick, a
Somerville graduate, in 1947. Bonsall and his wife were keen hill-walkers. He wrote two articles for The Scottish Mountaineering Club on the definition of a
Munro. After his retirement, Bonsall and his wife moved to Harrogate. ==Career==