| Cast | Jon Pertwee (as The Doctor), Caroline John (as Liz Shaw), Nicholas Courtney (as Brigadier Lethbridge-Stewart / Brigade-Leader Lethbridge-Stewart), John Levene (as Sergeant Benton / Platoon Under-Leader Benton, Primord Benton), Olaf Pooley (as Professor Stahlman / Director Stahlman), Christopher Benjamin (as Sir Keith Gold), Sheila Dunn (as Petra Williams / Dr Petra Williams), Derek Newark (as Greg Sutton), Ian Fairbairn (as Bromley), Walter Randall (as Harry Slocum), Derek Ware (as Private Wyatt), David Simeon (as Private Latimer), Roy Scammell (as RSF Sentry), Keith James (as Patterson), Dave Carter (as Primord), Pat Gorman (as Primord), Walter Henry (as Primord), Philip Ryan (as Primord), Peter Thompson (as Primord) |
