Although this was William Hartnell's last regular appearance as the First Doctor, he would reprise the role for the tenth anniversary serial The Three Doctors. As a result of his role as the astronaut Williams in this serial, the Bermudian-born Earl Cameron (who was 49 at the time of filming) reportedly became the first black actor ever to play an astronaut on television. He was also only the third actor from the series to reach 100 years of age, doing so in 2017. He died in 2020 at the age of 102, and although this was his only appearance in Doctor Who, he had a long and varied acting career both before and after this role. Missing episode The last episode of this serial is missing. It is one of the most sought-after of the missing episodes, because it contains the historic first regeneration scene (even though a low-quality, truncated copy of this sequence survives and is held in the BBC Archives), and also because it is William Hartnell's final episode. As such, it is included in a list of the twenty most wanted missing programmes (as drawn up by the British National Film Theatre) alongside the BBC studio footage from the Apollo 11 landings (which is currently held only in soundtrack form). Popular myth has it that the only surviving telerecording copy of the fourth episode was lost when loaned out to the children's programme Blue Peter in 1973 when they wished to use a clip from it in a feature on the tenth anniversary of Doctor Who. Although a print of The Daleks' Master Plan Episode 4 ("The Traitors") was loaned to Blue Peter and not returned to the BBC Film Library, there was never a copy of The Tenth Planet Episode 4 there to have been loaned. Another department – BBC Enterprises – was still offering all four episodes for sale to foreign broadcasters until the end of the following year and would not, in any case, have loaned out master negatives. In 1992, a man named Roger K. Barrett (later revealed to be an alias, based on the real name of Syd Barrett) claimed to have a videotape recording of Episode 4 of this story, and offered to sell it to the BBC for £500. Before this was revealed as a hoax, the BBC produced a special introduction for an intended VHS release of the story,