Special Guest Stars Edward Mulhare as Professor Mathers Guest Stars David McCallum as Gwyllim Griffiths Constance Cavendish as Gert "the Bread" Evans Jill Haworth as Cathy Evans Robert Doyle as Wilt Morgan Nora Marlowe as Mrs. Ives George Pelling as Policeman Uncredited Janos Prohaska as Darwin the Monkey