Willoughby was born in London, his mother Mary Henderson had married John Gray, who was killed in action in Iraq soon after his birth. (Though several sources suggest he was born in Aberdeen, Scotland). In 1918 Mary re married and Willoughby became the stepson of Lieutenant General Henry Pownall.  He achieved popularity in the mid-1950s after making 38 appearances on the television series The Adventures of Robin Hood. He appeared as ‘Pete’ in Harold Pinter’s The Birthday Party on its very first run in 1958, this being just one of countless stage performances he made. Though over-shadowed by his stage career, Gray made a handful of incredibly popular films, notably as a priest in Laurence Olivier’s film Richard III (1955), The Mummy (1959), Absolution (1978), The Hit (1984), the James Bond film A View to a Kill (1985) as retired Nazi doctor and Max Zorin (Christopher Walken) henchman Karl Mortner/Hans Glaub, and as the elderly and kind king in The Princess Bride (1987).  In the late 1980s, he appeared in the BBC drama Howards’ Way as banker Sir John Stevens. In Sergei Bondarchuk’s 1970 film Waterloo, he is credited as both an actor (playing Captain Ramsey) and a military consultant.  Gray died aged 76 in February 1993. His wife, who wrote as Felicity Gray,(Nee Margaret Andraea) was a choreographer, speaker and writer on ballet, who notably taught Gene Tierney for her role in Never Let Me Go.