He was born in York, Yorkshire, England. He was the second of three children and only son of Harry Miles, a draper, and his wife, Kate Elizabeth Hindley. He was educated at Bootham School, a Quaker foundation in York. However, from the age of 12, no amount of persuasion would make him conform to religious observance which he found unacceptable. From there he won an exhibition to King's College, Cambridge, to read medicine.[2] He qualified MRCS, LRCP in 1928 at St Bartholomew's Hospital, London and, in 1929, at a relatively early age, obtained MRCP and in 1937 FRCP.[2]
In 1946, he was appointed deputy director of the National Institute for Medical Research and head of its department of biological standards. His research concerned the mechanisms of inflammation and immunity.
From 1952–1971, he was director of the Lister Institute of Preventive Medicine. In 1952 he also became MD and professor of experimental pathology at London University. He was elected FRS in 1961. In total he published over 140 papers on his work and was joint editor of five editions of Topley and Wilson's Principles of Bacteriology and Immunity.
After retirement from the Lister in 1971, he continued to work, even after a stroke, till his death.[2]
In 1930 he married a medical laboratory technician, Ellen (Else) Marguerite (died 1988) who was the half-sister of the writer Roald Dahl.[3] They had no children. Miles died at his home, 7 Holly Place, Hampstead, London.[2]