Pioneer of the docudrama genre who made politically charged films such as Punishment Park and Culloden.
He began his career in advertising as an assistant producer, turning to filmmaking in the 1950s.
His docudrama The War Game, which won the 1966 Academy Award for Best Documentary Feature, was banned by the British government for two decades.
He had two children with his former spouse Francoise.
His letter to John Lennon inspired the singer to participate in his 1969 Bed-in and Peace Concert.
