(Robert) Geoffrey Trease FRSL was a prolific British writer who published 113 books, mainly for children, between 1934 and 1997, starting with Bows Against the Barons and ending with Cloak for a Spy in 1997. His work has been translated into 20 languages. His grandfather was a historian, and was one of the main influences on his work. He is best known for the children's novel Cue for Treason (1940).