I know some writers can deliver a book exactly when they say they will, but I honestly don’t know how they do it. For me a book is a journey and I don’t know how long it will take. I have a map, but it is sparse and there are so many things to see and learn and explore before I find what I set out to find. I write in order to think and that means I don’t know how long it will take me to figure it out. I think of it as a very organic process but that might be a nice way of saying ‘utterly disorganised’.

Despite the size of the books, I really have to work to fit everything into each one and I cut and cut and cut to do it. It’s hard work but incredibly satisfying, and it is balanced with elaborating and clarifying, because the stories are all very complex. For me the process of editing does not happen after the book is finished but is part of the whole creative process. Finishing will be a wrench in the same way that finishing Phillip Pullman’s His Dark Materials books were a wrench for me, as a reader, or the Narnia books when I was a kid … or Steig Larssen’s Millenium Trilogy. But they must be finished and that is that. And I want to finish them. I want to come to the end of it because I want to know exactly how it will all come out as well. But unlike readers, when I have finished, I will never ever be able to go back through the wardrobe door again. At least, not that door …

Is there any particular ritual involved in your writing process?