Over the years, I've been asked many times whether a particular novel is appropriate for a particular child when the content is potentially scary or adult. Since July 2000, my response to this has been determined by the death of Cedric Diggory and where the book stands in relation to it. Could your child cope with the murder of Diggory or not? If yes, this book is for you... if not... leave it a while.
For me, the death of Diggory is the turning point in the Harry Potter series, the moment at which the books cease to be children's novels. It is the moment at which Harry has full clarity for the first time about exactly what he is dealing with. By the time he returns to Hogwarts the following autumn, he is sullen and moody. Life at Hogwarts is no longer about Quidditch and chocolate frogs but about a battle for survival. And the reader knows that there are no limits to Rowling's ruthlessness with her characters, something that plays out shockingly in the final Battle of Hogwarts.
The Goblet of Fire is not my favourite of the books (that is The Half Blood Prince) but in many ways I think it's the one that best captures the brilliance of the whole series, and its pivotal moment is shocking and brutal.
It feels calculated and chilling, as if Rowling is shifting gears, and is another mark of her skill as a consummate storyteller, because the timing is just right.
I am an unashamed lover of the Potter series. Having been put on to it by a great friend at about the time The Prisoner of Azkaban was published I raced through the first three novels and became as impatient as a nine-year-old for each subsequent release. While at the Harrogate Crime Festival in July 2007, I queued at WH Smith at midnight with hundreds of others for The Deathly Hallows.
Over the years, I've wondered about why I enjoyed them quite so much, and often whether I have been influenced by my time at boarding school, which I loved, and was gripped by nostalgia. And perhaps that has something to do with it. But actually, I think it's really just the exquisite storytelling, the lavish attention to detail in the wizarding world and the heroism and selflessness at the heart of the storyline.
I love Stephen King's quote about the film: "Harry Potter is all about confronting fears, finding inner strength and doing what is right in the face of adversity."
Harry, Ron, Hermione and others are heroes you can root for, and Rowling tells the tale with such verve, drama and wit, the whole thing is rarely other than utterly gripping. On long car journeys now, with adult children, the books can be a feature of journeys. And 25 years on from the publication of The Philosopher's Stone, they are still, well, magic.