In 1960 Bannister appeared on stage at the Cambridge Theatre in London in Billy Liar, which starred Albert Finney. He starred as Darkie Pilbeam, a wartime spiv, in the 1968 television series The War of Darkie Pilbeam, and from 1969 to 1970 he appeared as "Heavy Breathing" in Jack Rosenthal's sitcom, The Dustbinmen. Shortly afterwards, he was asked to play Mr. Lucas in a Comedy Playhouse pilot called Are You Being Served? and took the part in the series. It was originally intended as a vehicle for him as the average man caught up in the store full of odd characters and baroque customs but, as it developed into more of an ensemble piece, he found his role being greatly reduced as other characters came to the top. He left the role in 1980, as filming for the show clashed with a lengthy tour for a play.