His father, Philip Guard, was an English stage actor, his mother, Charlotte Mitchell, an actress and poet.
As a 14-year-old, in The Go-Between (1971), Guard played Leo Colston, the title character who runs messages between two secret lovers and has a momentous 13th birthday.
Guard later appeared in Picnic at Hanging Rock (1975), The Count of Monte Cristo (1975) with Richard Chamberlain, Absolution (1978) alongside Richard Burton and Billy Connolly,[2] Gandhi (1982), and in P. D. James's An Unsuitable Job for a Woman alongside his cousin Pippa Guard.
On stage he played Christopher in a 1982 production of The Jeweller's Shop by Karol Wojtyła, later Pope John Paul II, at the Westminster Theatre, and appeared in a guest role in the 1983 Doctor Who story Terminus.
Guard is now a fully accredited child psychotherapist living in London and has written more than ten books for children,[4] including "Little Box of Mermaid Treasures", "Pirate Fun", "The Dragon Master's Tale", and "Secrets of the Fairy Ring".