The concept typically comes first. Those are the lightbulb moments, the most muse-y ones. For my first book, it was the idea of this uneasy trio involved in dream research, a romantic couple and their professor. For my second book, I knew that four siblings would visit a fortune teller, who tells them their dates of death (or so she claims), and that the book would then follow the siblings over the course of their lives. And for this new book, there were two threads—one was a fascinating (real!) science experiment that was producing results with eerie implications. And the second thread was my desire to explore the universe of marriage, or partnership.

Sometimes I like things I’ve written, but usually, when I’m revising it, I’m appalled by incoherence, wordiness, lack of specificity, boredom, like many other stylistic and material sins. It can get very dreary. I have revision techniques that can usually work to combat those errors.

I worked as an editor until I joined the New Yorker , and so I’m an extremely tough self-editor. I also love being edited. I love a hard edit. It’s a privilege to be edited hard.

While I was editing, sometimes I would have these free associations, so maybe I would not have had that shot of the naked people if I had not found the files. I allowed myself that things would happen in the film, even though I had organized my trip in the boat and to rebuild the courtyard, and all this.

The friends with whom I sat on graduation day have been my friends for life. They are my children’s godparents, the people to whom I’ve been able to turn in times of trouble, people who have been kind enough not to sue me when I took their names for Death Eaters.

Even though I have a highly visual imagination, I’ve had to learn just how much can be said onscreen without a word, and David and Steve have taught me that.

The same thing Molly Weasley saw when she let a Boggart out of the locked cabinet in ‘Order of the Phoenix’ – my loved ones, dead. If, however, you are talking about a fear that concerns only me, it would be being buried alive. I’m not sure how a Boggart would represent that; perhaps turn into a coffin around me? Urgh.

In my early twenties I wrote quite a lot of a very bad novel called The Private Joke. I regularly abandoned it for months at a time to write other things, then picked it up again. Part of the manuscript was sitting up in the luggage rack when, aged 25, I was travelling by train from Manchester to London, and the idea for a very different kind of book hit me: that of a boy who didn’t realise he was a wizard, and was taken off to magic school.

I couldn’t have asked for better collaborators on the stage play than John Tiffany (director) and Jack Thorne (writer).

I cannot possibly reveal the full horror of my most embarrassing moment, but it took place in a pub in Exeter (which is a town in the south coast of England, where I went to university) in 1984 and involved a joke made by me that backfired spectacularly. The whole debacle was witnessed by my friend Pauline, who is mentioned elsewhere on this fansite (I have to keep her happy in case she TELLS).