Brown was born at 21 Southampton Street, Redcar and attended Sir William Turner's (Coatham) School from 1937. At Durham University, he studied geology, being influenced by the teaching of Professor Lawrence Rickard (Bill) Wager.
Brown's first researches comprised a superb field and laboratory study of the layered ultrabasic igneous rocks of the island of Rum. Brown had visited the Skaergaard intrusion as a member of the east Greenland geological expedition led by Wager and W. A. Deer in the summer of 1953, further deepening the interest in layered igneous masses which was to last the rest of his life, culminating in the publication, with Wager, of the definitive monograph Layered Igneous Rocks, in 1968.
On his return from America in 1955 Brown became university lecturer in petrology at Oxford and in 1967 he was appointed to the chair of geology at his old university, Durham, in succession to Kingsley Dunham (q.v.). Brown's major scientific contributions during his years at Durham centred upon his part in the study of the first samples of rock from the moon, returned to earth by the Apollo 11 astronauts in 1968. His hypothesis, that the moon must in its early history have passed through a stage when it was essentially molten and behaved rather like a vast layered intrusion, at first met with some scepticism, but, with some modifications, steadily gained wide acceptance.