Despite the fact that regeneration is an important part of the mythology of the franchise, Doctor Who almost undermined its first regeneration. The concept of regeneration is key to the longevity of Doctor Who, as it allows a BBC TV show to change its lead actor whenever someone wants to move on. Revival stories often give Doctor Who the opportunity to reinvent itself, and in recent years the showrunner has often changed at the same time as the Doctor’s departure.
The first revival—when William Hartnell turned into Patrick Troton— occurred in the 1966 season 4 story “The Tenth Planet”. Hartnell’s health was deteriorating; he suffered from undiagnosed atherosclerosis, and his influence was most noticeable in that it affected his ability to learn his lines. Changing production groups didn’t help matters, and Hartnell increasingly encountered them behind the scenes.
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In fact, Hartnell had come close to quitting a few months earlier, in the Doctor Who season three story “The Heavenly Toymaster.” His contract was about to expire, and producer John Wiles, frustrated by their hostile relationship, came up with a plan to exclude Hartnell from the show. This villain of the Doctor Who story was a Toyboy who could rewrite reality at will, and for most of the story the Doctor was invisible and even mute. Wiles intended to end the story by having the Toy Maker make the Doctor visible again, but show that he now had a completely different face. However, Wiles’ superiors rejected his decision, and Hartnell stayed for some time. When he finally left, a completely different mechanism was used to discharge him, which guaranteed the longevity of Doctor Who, since, unlike the approach proposed for the “Heavenly Toy Manufacturer”, it could be repeated.
What would have happened in Doctor Who if John Wiles had followed his Hartnell plan
It’s easy to forget that the Doctor’s story has only been researched for decades. The Time Lords themselves are a clumsy retcon, completely at odds with the original dialogue explaining the origin of the Doctor in the first episode “Unearthly Child”. There, the Doctor suggested that he and his granddaughter Susan were exiled from their people, lost in the fourth dimension of time, and indeed, he was introduced as the man who invented the TARDIS, and Susan as the one who gave her a name. In many stories, it was assumed that the Doctor was human — there was definitely no hint of two hearts — and it was only when the Doctor regenerated in the Tenth Planet that his alien nature became truly clear. The Time Lords themselves did not appear until the 1969 Doctor Who War Games, although it was another five years before their image was really blocked.
Thus, the mythology of Doctor Who is accretionary in nature. It’s amazing to imagine what would have happened if Wiles had achieved his goal in 1966, when Hartnell left in rewriting reality rather than updating. The series would certainly go in a completely different direction, but the decision to make the change of the main character a one-time event would make it difficult to repeat Doctor Who. Regeneration allowed Doctor Who has been around for 60 years, and Wiles’ idea wouldn’t have done the same.