 Campbell was born on 16 July 1915 at Ellerslie Station, near Adelong, New South Wales.He was the third child of Australian-born parents Alfred Campbell, a grazier and medical practitioner, and his wife Edith Madge, née Watt.In 1930, Campbell went to The King's School, Parramatta, and in 1935, with the support of the headmaster, he enrolled at Jesus College, Cambridge, graduating with a Bachelor of Arts in 1937.