Denborough was born in Salisbury, Rhodesia to Paul Peter Denborough and Alma Mary Hepburn. He was educated at Prince Edward School in Salisbury and the University of Cape Town before being awarded a Rhodes Scholarship to Exeter College, Oxford, where he was an assistant at the Nuffield Department of Clinical Medicine, Radcliffe Infirmary. He married Erica Elizabeth Griffith Brown on 12 December 1959. He was Resident Medical Officer at National Heart Hospital in London in 1958 before travelling to Australia, where he was First Assistant at the University of Melbourne and Royal Melbourne Hospital from 1960 to 1968, Reader in Medicine at the University of Melbourne from 1972 to 1974 and was a Professorial Fellow at the John Curtin School of Medical Research in Canberra from 1974 to 1991, working as Acting Head of the Department of Clinical Science from 1975 to 1981 and Acting Director of the Centre for Resource and Environmental Studies in 1982. He edited The Role of Calcium in Drug Action, the research for which centred on malignant hyperthermia which he described in 1962 and tentatively linked with Sudden Infant Death Syndrome. From 1992 to 1994 he was Professor of the John Curtin School of Medical Research at the Australian National University, retiring in 1995. He later became an Emeritus Professor.
Denborough founded the Nuclear Disarmament Party (NDP) in 1984 and contested elections on its behalf numerous times. He published Australia and Nuclear War in 1984. NDP Senators Jo Vallentine and Robert Wood were elected in 1984 and 1987 respectively.
In 2003 he conducted a lone vigil for 52 days outside Parliament House, Canberra, in protest at what he considered was the unjust invasion of Iraq.
- "True Stories: Sudden Death". Australian Broadcasting Corporation. 26 June 2003. Retrieved 8 August 2011.
- Who's Who in Australia (2011). Denborough, Michael Antony (password required)
- David Denborough, Obituary: "Life-saving researcher fought nuclear power", The Age, 18 April 2014
- Brisbane Times, 18 April 2014, "Life-saving researcher fought nuclear power". Retrieved 21 April 2014