Graham Leslie Bennett was born in Moonta South Australia, and educated at Prince Alfred College and St Mark's College, where he was college president. He graduated MB BS (Adelaide) with credits in 1935. After four years in country practice at Freeling, he joined the Australian Imperial Force serving in New Guinea and attaining the rank of major. After the war, he joined a rapidly expanding general practice at Woodville, and after a year's study leave, gained the MRACP in 1953, (FRACP 1973). He then served as a general physician in a group practice. He was an excellent and caring physician, intent on providing a first rate service for his patients, by whom he was greatly liked and respected.
Ill health early in his career curtailed his tennis and golf, and his main interest outside medicine and his family was medical politics. He was first elected to the South Australia branch of the British Medical Association in 1947, proceeding to branch president in 1955 to 1956. After the formation of the Australian Medical Association (AMA), he was appointed a federal councillor from 1962 to 1970, resigning because of ill health. He served on numerous committees including the medical services committee of enquiry, the repatriation drug committee, the Medical Defence Association of South Australia (chairman 1976 to 1978), the Medical Benevolent Association from 1961 to 1978, and the Dental Board of South Australia 1957 to 1970. He was made a fellow of the AMA in 1970.
Graham Bennett was a logical, articulate and lucid speaker, with the ability to summarise a discussion and propose a compromise solution; perhaps these were family traits as the same applied to his two distinguished brothers, Trevor, a lawyer and Dick, professor of surgery at St Vincent's Hospital, Melbourne. Graham's life was greatly affected by the early death of his first wife, Helen, and later of their only son, Robert; and then by severe hypertension and leukaemia. He bore these adversities with uncomplaining courage. He married Joan Chesterman (née Hudson), a New Zealand war widow. They had three children, one of whom practises medicine in Adelaide.