More than once in TOTP clips from the late 70's - including once on stage with Jimmy Savile
I did an episode of Crystal Maze.
(under Ed Tudor Pole, rather than Richard O'Brien unfortunately).
Would give an arm and a leg to be on Doctor Who.
Michael McIntyre's Comedy Roadshow in Brighton, after about 30 seconds it cut to a close-up of me in the audience, my parents were in it too but my mate got completely cut out of the shot. It's on YouTube somewhere but I haven't got access from work.