The Doctor (Doctor Who) footage. Tom Baker did reappear, but as "the Curator", an ambiguously different character who he was not credited for playing. A voice actor, John Guilor, recorded a line of audio impersonating the First Doctor, for which he was credited as "Voice Over Artist". In other multi-Doctor stories, the multiple actors are all credited as "The Doctor", the exception being "The Three Doctors" (1972–73), which credited William Hartnell, Patrick Troughton and Jon Pertwee as "Doctor Who" as the 1972 serial preceded the practice of crediting the character as "The Doctor". In "Human Nature" (2007), the plot involves the Tenth Doctor altering
The Sixth Doctor: The Last Adventure of "Time and the Rani", but due to the firing between seasons of Sixth Doctor actor Colin Baker, the episode gave the event very little screen time and didn't explain what had caused it. Big Finish Productions producer David Richardson approached Baker in 2014, after seeing "The Time of the Doctor", which had depicted (on television) the regeneration of the Eleventh Doctor into the Twelfth: "I felt very strongly that regeneration stories, and each Doctor’s final end, are very important to "Doctor Who" fans – these are stories that allow us to see the Doctor at his most courageous, making