 In May 1946, Moyle was appointed as Parliamentary Private Secretary to the Prime Minister, Clement Attlee, following Geoffrey de Freitas who had been given a ministerial post.The appointment gave Moyle a central role in managing relations between Attlee and government backbenchers, and almost silenced him in the chamber of the House of Commons.Attlee gave his PPS access to almost all important decisions, and respected Moyle's advice on the sometimes fractious Parliamentary Labour Party.