as Peter Burroughs

as Ted Fleming

as Colonel White / Captain Black / The Mysterons (voice)

as Polly's Husband (uncredited)

as William Peck

as Don (as Eldred Tidbury)

as Inspector Wills

as Jimmy Thompson

as Captain White / Captain Black / The Mysterons (voice)

as Stukely

as Robert Maitland

as Young Yacht Guest (uncredited)

as James Martin

as Extra (uncredited)

as TV Program Announcer (uncredited)

as Captain Ross

as Headmaster

as Albert de Courcey

as Col. George Gordon

as The Mysterons / Colonel White / Captain Black (voice)