A British actor who worked predominantly in television, Cannon appeared in several Doctor Who (1974-1983) stories during the Jon Pertwee and Patrick Troughton eras, as well as numerous episodes of classic television shows such as Steptoe & Son, The Sweeney, Porridge and The Professionals. His other credits included Beau Geste (1982), The Adventures of Sherlock Holmes (1984) and as a Stormtrooper in Star Wars: Episode IV - A New Hope, Star Wars VI - Return of the Jedi and as a Holographic Imperial Officer in Star Wars Episode V - The Empire Strikes Back.