Sydney Newman Creator Jon Pertwee Dr. Who Actor Caroline John Liz Shaw Actor Nicholas Courtney Brigadier Lethbridge-Stewart Guest Star Olaf Pooley Professor Stahlman Actor Ronald Allen Ralph Cornish Actor Christopher Benjamin Sir Keith Gold Actor Derek Newark Greg Sutton Actor John Abineri Carrington Actor William Dysart Reegan Actor Norman Jones Major Baker Actor Sheila Dunn Petra William Actor Ric Felgate Van Lyden Actor Thomasine Heiner Miss Dawson Actor Paul Darrow Captain Hawkins Actor Pat Gorman Silurian Actor Dave Carter Old Silurian Actor Peter Halliday Silurian Voice Voice Ian Fairbairn Bromley Actor Neville Simons Astronaut Actor John Levene Sergeant Benton Actor Timothy Combe Director Michael Ferguson Director Douglas Camfield Director Derek Martinus Director Don Houghton Writer David Whitaker Writer Malcolm Hulke Writer Robert Holmes Writer Barry Letts Director