Wow, now that is the toughest question because you always feel like you are betraying one character when you name another. I actually can’t do it. I can say why I loved a few of the characters, though the truth is I could tell you why I loved at least one and usually more characters in every book I have written. But let’s choose a few. I like Elspeth because she is like another me. She is the inside me. She is the skin I slipped into when I was fourteen and wanted to think about things, and she has grown with me, though not as fast. She is powerful and prickly and assertive and tall and lean – all the things I am in my imagination. She is brave and truthful and all the things I would be if I were better. She is me as a hero.

Nissa is her in urban guise, but the main character in The Gathering, and the one I like most, is Nathanial, because unlike Nissa he can be soft. I love Billy Thunder because he is the kindest, sunniest, most sheerly good character I have ever created. I love Maruman because of his madness and his sheer bloody-mindedness. I love Mr Walker because he is a pernickity little scold. I love Fork because, in the most true and metaphysical sense, it is shaped by the lives of the people and creatures who inhabit it. I love Little Fur for her gentleness and Crow for his rudeness and, oh, I love Sorrow for his great, terrible mythic sadness.

I guess I am never going to write an anti-hero, but what I like doing is taking a character and making them seem comical or cowardly or silly, and then producing a paradigm shift so that we can see that all of these things can hide incredible courage, depth and blinding beauty of spirit. I always suspect it of my characters, and when it comes I am always shocked and touched by it. I guess that is the thing I love most about writing: the moment when a character I have created reveals the bit of itself that I did not invent or expect. The bit where they take on their own life …

The last instalment of the Obernewtyn series, The Red Queen, isn’t far from being released. How difficult is it to close a series that’s been with you for so long?

It’s further away than my fans or publisher likes. It was supposed to come out this year but I found I just could not work when the book was scheduled and everyone was hanging on me finishing. It was like trying to work in a room where people were shouting at you that you were going to miss the bus. Luckily, Penguin have been able to bear with me and the final book will be coming out next year.