John Christopher is a pseudonym for Samuel Youd. He has written under the pseudonyms John Christopher, Stanley Winchester, Hilary Ford, William Godfrey, Peter Graaf, Peter Nichols, and Anthony Rye.
Nice interview here from April 10, 2009:
http://www.colinbrockhurst.co.uk/interview-with-tripods-author-sam-youd-aka-john-christopher/380/
