Geoffrey de Crespigny was born in Glenthompson, Victoria, the son of the local general practitioner, Constantine Trent Champion de Crespigny who was later to become a prominent physician in South Australia. After an initial attendance at Queen's School in North Adelaide, he finished his secondary education at Geelong Grammar School and then entered his father's old medical school in Melbourne as an undergraduate at Trinity College. He excelled in rowing and was a member of the University of Melbourne crew in 1927-29. After graduation, he was a resident medical officer at the Adelaide Hospital and shortly after undertook postgraduate studies in England. On his return in 1933, he married Kathleen, daughter of Sir Edward Cudmore, a leading surgeon of that time. They had one child, Dr Rafe de Crespigny who became a reader in Chinese at the Australian National University.

After a short period in general practice he enlisted in the Australian Imperial Force and served in the Middle East and New Guinea rising to the rank of lieutenant-colonel. His extended period of nine months in Tobruk, earned the nickname of `The old man of Tobruk', and he was later mentioned in dispatches. He continued his military career after the War in the Citizen Military Forces, and retired with the rank of colonel in 1959. Shortly after he was awarded the Order of the British Empire.

Geoffrey de Crespigny had shown a great fondness for children early in his career and subsequently, after many years in more junior appointments, he was appointed an honorary physician at the Adelaide Children's Hospital in 1949. An attention to detail, no doubt an inheritance of his military experience, was always manifest in his ward rounds. He was an active member of the state branch of the British Medical Association of which he was the president in 1960. Both on the branch council and at meetings of the medical staff of the Adelaide Children's Hospital, he was particularly able at bringing order out of chaos by the happy faculty of framing a resolution which perfectly met the need. He was on the state committee of the College from 1948-56 and 1960-64 and he was the honorary treasurer of the Australian Paediatric Association in 1957 and 1958.

He gave up private practice in 1960 to take on the medical directorship of the Mothers' and Babies' Health Association and with his high administrative acumen successfully guided it in a programme of reorganisation and expansion.

His quiet dignity and charm were felt by all who met him. In his later years he and his wife (also an indefatigable worker for the Adelaide Children's Hospital and the MBHA) travelled widely including attendances at several international paediatric congresses. One could imagine no better ambassador for Australian paediatrics.