 He married Lady Camilla Osborne in 1977 (divorced 2002).She was the former wife of Robert John Brownlow Harris and was the daughter of John Osborne, 11th Duke of Leeds and his second wife, Audrey Young.By his second marriage, Dempster had a stepdaughter, Emily Kate Godolphin Harris (born 1972), and a daughter, Louisa Beatrix Dempster (born 1979).