final serial, The Tenth Planet (first broadcast in October 1966), some of which is shown at the start of the special. During the last episode's final moments, the Doctor leaves his companions Ben and Polly and returns to the TARDIS; they find him collapsed in the console room, where he undergoes his first regeneration. Derek Martinus, the episode's director, reportedly cut a line from the original script which suggested that the Doctor was refusing to give in to the regeneration process. Steven Moffat's 2017 story creates an extended narrative around that part of the story, in which the First Doctor delays his regeneration and encounters his future self — the Twelfth Doctor — in the snowy wasteland. When Testimony shows the First Doctor images of his future incarnations, clips from both the classic series and the revival are used, including the Third Doctor from Invasion of the Dinosaurs (1974); the Fifth Doctor from Arc of Infinity (1983); the Seventh Doctor from The Happiness Patrol (1988); the Eighth Doctor from "The Night of the Doctor" (2013); the Ninth Doctor from "The Parting of the Ways" (2005); and the Tenth Doctor from "The Waters of Mars" (2009). Testimony also lists several of the Doctor's future titles: "The Shadow of the Valeyard" (from The Trial of a Time Lord, said to be a distillation of the Doctor's darker side), "the Oncoming Storm" ("The Parting of the Ways"), "the Imp of the Pandorica" (a reference to the Eleventh Doctor story "The Pandorica Opens"), "the Beast of Trenzalore" ("The Time of the Doctor"), "the Butcher of Skull Moon" and "the Doctor of War" ("Hell Bent"). "The Destroyer of Skaro" refers to the destruction of the planet in Remembrance of the Daleks (1988), although Skaro was later restored, as explained in "Asylum of the Daleks" (2012) and shown in "The Magician's Apprentice" (2015). The Weapons Factories of Villengard were originally mentioned in "The Doctor Dances" (Steven Moffat's first Doctor Who story), where the Ninth Doctor implied that he was responsible for their destruction. Helen Clay, who would become Testimony's glass pilot, was from New Earth and lectured at "New Earth University," a reference to the Tenth Doctor stories "New Earth" and "Gridlock". Outside references The Doctor addresses his original incarnation as "Mary Berry", "Corporal Jones", and "Mr Pastry". Mr Pastry was a comedic variety stage act and children's show character played by actor Richard Hearne, who