Guest Stars Lynda Bellingham as The Inquisitor Michael Jayston as The Valeyard Honor Blackman as Professor Lasky Malcolm Tierney as Doland Yolande Palfrey as Janet Leon Davis as Ortezo Michael Craig as Commodore Travers Denys Hawthorne as Rudge Arthur Hewlett as Kimber Sam Howard as Azta David Allister as Bruchner Simon Slater as Edwardes Tony Scoggo as Grenville Hugh Beverton as Guard Tony Scoggo as Hallet Mike Mungarvan as Duty Officer Uncredited Robert Goodman as Hyperion III Officer Barbara Ward as Ruth Baxter Richard Bonehill as Hyperrion III Guard