He was the son of the art historian Lord Clark of Saltwood (Sir Kenneth Clark), and the younger brother of the Conservative politician and military historian Alan Clark, with whom he was not always on good terms. Born in London, he was educated at Eton College and Christ Church, Oxford. From 1951 to 1953, he did National Service as a pilot officer in the Royal Air Force. In that capacity, he flew the Handley Page Hastings aircraft to Malaya and the Middle East. Colin Clark's first job on leaving university was as a personal assistant on the film The Prince and the Showgirl (1957), directed by Laurence Olivier and starring Olivier and Marilyn Monroe, an experience Clark later turned into two books – The Prince, the Showgirl and Me and My Week with Marilyn – the former a set of diaries (a TV documentary version of which was also made in 2004) and the latter a memoir of his alleged relationship with Monroe. Clark's time with Monroe is the basis of the 2011 film My Week with Marilyn, where he is portrayed by Eddie Redmayne. He went on to work with Olivier on The Entertainer, Titus Andronicus and other British stage productions. In January 1958 he agreed to be bound over having been rounded up in a police raid on John Aspinall's illicit gaming house. He then worked for Granada Television in Manchester, initially as a floor manager and later as assistant to studio boss Denis Forman and then head of design. Moving to New York in 1960, he was involved in setting up a PBS educational television station, Channel 13 New Jersey, with the aim of covering arts and culture in the New York region. He made a series of programmes called Art: New York, and recorded live concerts by Thelonious Monk and Sonny Rollins. Clark returned to Britain in 1965 to work for Associated Television (ATV), where he made many documentary films, including series with Angus Wilson and Bernard Levin, as well as directing a series on art appreciation presented by his father, Sir Kenneth Clark, who had fallen out with the BBC. After leaving ATV in 1971 to work as an independent film producer, he made further cultural documentary films for various commercial sponsors and for the Getty Museum as well as a film in which Alistair Cooke interviewed Prince Charles. Although much of this work was for the American market, he ran the operation partly from London because costs there were lower and because, he said, there was little American tradition or experience of making documentary films. Clark was briefly married to prima ballerina Violette Verdy in the 1960s. Their marriage ended in divorce. He retired from filmmaking in 1987 to write books. He died in December 2002 in London.