While it was built to be a bus conductor by Bellboy, the chief clown had it programmed to kill on the Master. It was loved by the audiences they initially had to the Psychic Circus. (AUDIO: The Psychic Circus) It killed Flowerchild and was about to kill the Seventh Doctor, Ace, Captain Cook and Mags but the Doctor managed to disable it.
Later, the chief clown forced Bellboy to fix the bus conductor, and the robot clowns took it back to the bus. Kingpin and Ace went to collect something hidden aboard the bus and the bus conductor tried to kill them, but at that point Kingpin regained his memory and remembered how to destroy it.