With his twin brother Roy, a leading figure of the post-WWII British film industry. Though they alternated producing and directing chores, the brothers' individual filming styles were virtually indistinguishable. They formed Charter Films in 1937 and were responsible for gritty dramas such as "Thunder Rock" (1942) and "Brighton Rock" (1947) in the 40s. The team concentrated, during the next decade, on mildly anarchic comedies like "Private's Progress" (1956) and "I'm All Right, Jack" (1959), a satire of British trade unions.

During the Spanish Civil War John had fought with the Republicans and, though he later eschewed left-wing politics, all his films carry a degree of social comment. In WWII he made films for the Royal Air Force while Roy directed for the Army Film Unit.