Billie Davis had an uncredited role as a member of the Tribe of Gum in the Doctor Who television story An Unearthly Child.[1]
According to the Internet Movie Database, the Billie Davis who appeared in the story was the Surrey-born female pop singer who had (in 1963) recently enjoyed a major hit with her record "Tell Him". However, the more authoritative DVD Production Notes for An Unearthly Child indicate that the Billie Davis who appears in the story was actually a male actor cast as one of the tribesmen.