Sonia Melchett was born Sonia Elizabeth Graham in India, the daughter of a British army officer and his wife. She was educated in England at the Royal School, Bath. In 1947, she married the Hon. Julian Mond, son of Henry Mond, 2nd Baron Melchett, with whom she had three children. When her husband inherited his father's title, she became Lady Melchett. The family lived in London, where she was a well-known socialite, and on a farm near Hunstanton in Norfolk. She is the author of two volumes of memoirs, Someone Is Missing (1987) and From the Ganges to the Thames (2016), as well as Passionate Quests: Five Modern Women Travellers (1992). She also contributed a chapter to Sons and Mothers (1996), edited by Victoria Glendinning. In 1984, after the death of her first husband, she remarried to Andrew Sinclair, also a writer.