 His father was Arthur Moyle who was a Labour Member of Parliament and served as Parliamentary Private Secretary to Clement Attlee.Moyle was educated in Bexleyheath and Llanidloes, and at the University College of Wales, Aberystwyth and Trinity Hall, Cambridge, where he chaired the Labour Club in 1953.He became a barrister, called to the bar by Gray's Inn in 1954.