How was J. K. Rowling’s Harry Potter and the Philosopher’s Stone written? As a childhood paracosm? Or by a child-aged alternate personality?

Reading this first novel of the Harry Potter series, I have noticed certain unnecessary inconsistencies. I don’t mean big things, like the fact that Harry can fly on a broom instinctively, while other magic needs training, special words, potions, etc. I accept that Harry, as the hero, must be granted some innate superiority. The story requires it, so it doesn’t bother me.

The implausibilities I mean are trivial, unnecessary ones, like the fact that the boarding school for wizards, which is so magical in many ways, has cold hallways in winter. If it doesn’t have central heating, why doesn’t it have some magical way to heat the hallways? I don’t believe that an adult narrator would have been comfortable with that kind of inconsistency. It is not necessary for the story, and it would violate an adult author’s sensibility.

Perhaps the story was written in childhood: a paracosm, an imaginary world, comparable to the one created in childhood by the Brontës. Or perhaps the story was written in adulthood by a child-aged alternate personality.

We know that Joanne Rowling is an adult, but how old is J.K.?

J. K. Rowling. Harry Potter and the Philosopher’s Stone. London, Bloomsbury, 1997/2004.