In an internal memo dating from 1966, producers outlined how the original Doctor, William Hartnell, would be transformed for his successor Patrick Troughton.
It also tackled the “horrifying experience” of the regeneration.
“The metaphysical change… is a horrifying experience – an experience in which he relives some of the most unendurable moments of his long life, including the galactic war,” it said.
“It is as if he has had the LSD drug and instead of experiencing the kicks, he has the hell and dank horror which can be its effect,” the memo added.
Discussing his appearance, the document stated: “His hair is wild and his clothes look rather worse for wear (this is a legacy from the metaphysical change which took place in the Tardis).”
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