Guest Stars Lynda Bellingham as The Inquisitor Michael Jayston as The Valeyard Honor Blackman as Professor Lasky Yolande Palfrey as Janet Sam Howard as Azta Malcolm Tierney as Doland Arthur Hewlett as Kimber Denys Hawthorne as Rudge Michael Craig as Commodore Travers Leon Davis as Ortezo 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