He was the son of Albert Reeves, an accountant and Ethel Blenche who was the daughter of a school mistress from Yarm, Teesside, they met while on holiday in Switzerland. Subsequently they lived in Nottinghamshire where they had two children, David and John, who later changed his name to James. He was born in Harrow, and educated at Stowe School and Jesus College, Cambridge. He taught until 1952, when he became a full-time writer.

He was close to Laura Riding for a time, being successor to Jacob Bronowski as editor of Epilogue: a critical summary. He was also an editor of some of the works of Robert Graves. His prose work for children commenced in 1956 and included short stories and poetry.