He is the eldest son of the publisher Rupert Hart-Davis and the brother of television broadcaster and author Adam Hart-Davis and Bridget, the dowager Lady Silsoe. His biography of his godfather, the adventurer and writer Peter Fleming, entitled Peter Fleming: A Biography, was published in 1974.

He is a direct descendant of King William IV and his mistress Dorothea Jordan and is therefore fifth cousin once removed of Queen Elizabeth II, second cousin once removed of the Conservative party leader David Cameron and first cousin once removed of the historian John Julius Norwich.

Partial bibliography of works by Duff Hart-Davis

• Mammoth book of spy thrillers (1989) ISBN 0-88184-481-0
• Armada (1988) ISBN 0-593-01231-3
• Ascension: the story of a South Atlantic Island (1973) ISBN 0-385-00314-5
• Audubon's elephant : America’s greatest naturalist and the making of the Birds of America (2004) ISBN 0-8050-7568-2
• Behind the scenes on a newspaper (1964)
• Fauna Britannica : the practical guide to wild & domestic creatures of Britain (2002) ISBN 0-297-82532-1
• Fire falcon (1983) ISBN 0-224-02080-3
• Further country matters (1992) ISBN 1-85310-323-3
• Gold of St. Matthew (1970) ISBN 0-09-456890-1
• Gold trackers (1970)
• Heights of Rimring (1980) ISBN 0-224-01837-X
• Hitler's games : the 1936 Olympics (1986) ISBN 0-06-015554-X
• Honorary tiger : the life of Billy Arjan Singh (2005) ISBN 81-7436-405-6
• Horses of war (1991) ISBN 1-85619-062-5
• House the Berrys built Concerns the history of the ''Daily Telegraph from it's inception to 1990. Illustrated with references and illustrations of William Ewart Berry, 1st Viscount Camrose (later called Lord Camrose).
• Level five (1982) ISBN 0-689-11257-2
• Megacull (1968) ISBN 0-09-455760-8
• Monarchs of the glen : a history of deer-stalking in the Scottish highlands (1978) ISBN 0-224-01463-3
• Peter Fleming : a biography (1974) ISBN 0-224-01028-X
• Raoul Millais : his life and work (1998) ISBN 1-85310-977-0
• Spider in the morning (1972) ISBN 0-09-458610-1
• Wildings : the secret garden of Eileen Soper (1991)
• End of an era : letters and journals of Sir Alan Lascelles, 1887-1920 (1986) ISBN 0-241-11960-X

Footnotes