Jon Pertwee Dr. Who Actor Caroline John Liz Shaw Actor Nicholas Courtney Brigadier Lethbridge-Stewart Actor Olaf Pooley Professor Stahlman Actor Christopher Benjamin Sir Keith Gold Actor Derek Newark Greg Sutton Actor Sheila Dunn Petra Williams Actor John Levene Platoon Under Leader Benton Actor Ian Fairbairn Bromley Actor Derek Ware Private Wyatt Actor David Simeon Private Latimer Actor Douglas Camfield Director Don Houghton Writer Barry Letts Director