Twice Upon a Time (Doctor Who) and Time". This makes him the third actor to play the role in the television programme, after William Hartnell and Richard Hurndall (in 1983's "The Five Doctors") since the premiere of "Doctor Who" in 1963. Bradley previously played Solomon in the 2012 episode "Dinosaurs on a Spaceship". The first trailer for the episode was shown during the 2017 San Diego Comic-Con, revealing the return of Polly, a companion from the end of William Hartnell's tenure as the First Doctor, portrayed by Lily Travers, and Pearl Mackie as Bill Potts. Also confirmed were appearances by Toby Whithouse, writer of seven episodes
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