Ratcliffe was the son of Samuel Ratcliffe, journalist, and his wife, Katie Maria nee Greaves. He was educated at Oxford and obtained first class honours in zoology under Sir Julian Huxley. In 1929 he came to Australia under the auspices of the Council for Scientific and Industrial Research (C.S.I.R.) to study flying foxes in Queensland and northern new South Wales.He returned to Australia again in 1935 to work for C.S.I.R. on wind erosion. In 1937 Ratcliffe moved to Canberra as senior research officer in C.S.I.R.'s division of economic entomology. During the war he directed the Army's efforts against malaria, scrub typhus and dengue fever. Ratcliffe returned to C.S.I.R. and became officer-in-charge of the wildlife survey section, testing the introduction of the myxoma virus to control rabbit numbers. In later years Ratcliffe was a leading figure in the founding of the Australian Conservation Foundation and its honorary secretary from 1964. He retired from the C.S.I.R.O. in 1969.
