without resolution to the plot, with the final battle taking place in another dimension against a being called Azlan who was controlling Mestor all along. The cat badge worn by the Sixth Doctor on his lapel for this story was handmade and painted by Suzie Trevor and purchased for the programme from a specialist badge shop in central London. For each subsequent story, the Doctor was to wear a different cat badge to symbolise that he was a "travelling cat of different walks." Besides being adjusted for the new Doctor, the opening credits underwent additional modifications with this episode. A prism-colour effect is added and the series logo takes on a somewhat bluish hue (which also results in it appearing slightly curved in comparison to the version introduced during Tom Baker's era). The theme music remains the same version as that introduced in 1980. Prior to this, the opening sequences of the Second, Third, Fourth, and Fifth Doctor eras had incorporated a still photograph of the lead actor. For the Sixth Doctor opening this was changed to using two photographs – one of the Doctor with a smile which changes to a second image showing the Doctor grinning. This limited animation would continue with the opening sequence for the Seventh Doctor. Cast notes Colin Baker also provides, uncredited, the voice of a Jacondan at Freighter Control in part three. Dennis Chinnery had previously appeared as Albert C. Richardson in the William Hartnell story The Chase and as Gharman in the Tom Baker story Genesis of the Daleks. Edwin Richfield had previously appeared as Captain Hart alongside Jon Pertwee's Doctor in The Sea Devils. Kevin McNally later played Henry in the audio play Spider's Shadow, and Professor Eustacius Jericho in the Jodie Whittaker episodes Village of the Angels, Survivors of the Flux, and The Vanquishers . Seymour Green had previously played Hargreaves in The Seeds of Doom. Helen Blatch had earlier been a voice artist in The Deadly Assassin. Outside references Shortly before the Doctor assaults Peri in a paranoid rage, he quotes the line "One morn a peri at the gate Of Eden stood disconsolate" and asks Peri to identify its author. The answer is Thomas Moore, in his poem Lalla Rookh. The first two instalments of the BBV Stranger video series appear to borrow the premise of the Doctor's desire to become a hermit to atone for mistakes he