"John Christopher" is a pseudonym for Samuel Youd, a prolific author whose full bibliography runs to around 70 novels under seven different names. His best work, and both of his lasting reputations (for apocalyptic disaster novels, 1955-66, and for children's adventure stories, 1967-) go under the name "John Christopher", so I shall call him that.
John Christopher was born in Lancashire, in 1922. In 1932 he moved to Hampshire and attended Peter Symonds' School, Winchester, until the age of 16, when he left to work in local government. At school he had been "absolutely passionately devoted" to science fiction, and in his teens he published an amateur magazine (The Fantast). He admired Aldous Huxley and Arthur Clarke, at the literarily serious end of the spectrum.
After war service in the Royal Signals Corps (1941-6), a path also followed by Kingsley Amis, his ambitions were more conventionally literary. The Rockefeller Foundation awarded him one of a number of grants for aspiring writers whose careers had been interrupted by war, and it enabled him to complete his first novel, The Winter Swan (published 1949).
Christopher, or rather Youd, is married, has four daughters, a son and grandchildren. He now lives in Rye, a small coastal town in the Sussex Downs, and part of the filming of the BBC Tripods took place in the fields near his house.
Christopher died 3 February 2012.