I am assuming, given that this is The Telegraph and not The Beano, that I do not have to point out that the Harry Potter books are children's books. But given the number of seemingly intelligent, normal adults who display not the slightest embarrassment discussing the finer points of quidditch with other adults, or who are perfectly happy to sit on a train, in full view of the rest of the carriage, reading any of the four previous instalments, I am probably making an assumption too far.