Making a name for himself on stage, notably in Noël Coward's Private Lives, Standing made his film debut in The Wild and The Willing in 1962; in 1964, he inherited his father's aristocratic title, as 4th Baronet Leon. His other film credits have included King Rat, The Elephant Man (with John Hurt), Chaplin (with Robert Downey, Jr. in the title role), Mrs. Dalloway, and V for Vendetta. Television work, in both the United States and England, has included Tinker, Tailer, Soldier, Spy (as Sam Collins) and guest spots on Hunter, Murder, She Wrote, Eerie Indiana, Midsomer Murders, and NYPD Blue. Along with David Healy, Standing appeared in a 1995 CD-Rom adaptation of the Clue board game, appropriately cast as Colonel Mustard.