David Smart (in-universe)

David was a ringmaster in a circus, and the sister of Gabriella. (TV: Billy Smart's Children's Circus)

Biography
While waiting for his sister Gabriella to do her act, Dr Who showed up in the Whomobile with her. Gabriella then went off again with Dr Who to find the rest of her dogs. (TV: Billy Smart's Children's Circus)

Behind the scenes
David Smart portrayed himself in Billy Smart's Children's Circus.