There's always a choice,' said Torak, and walked backward off the cliff.

To get the feel of the polar night, I went back to Spitsbergen in winter. I went snowshoeing in the dark and experimented with headlamps and climbed a glacier in driving snow.

Have you ever held a snake? They are so strong. You can see why there are so many myths about them: they are unlike any other creature. It's extraordinary how that little brain can keep everything moving in different directions.

I wanted to write a very simple story about a boy, a wolf, a girl, a bear and a forest, so I thought I might set it in the past. I didn't realise that it went back to when I was 10: I used to love the Stone Age when I was a kid and wanted to live in it, and I got rid of my bed and slept on the floor, but I didn't remember it.

When a wolf doesn't want to do something, they look really cute.

When my father was diagnosed with terminal cancer in 1991, I asked him if he had any regrets, and he said no. I was a burnt-out litigation solicitor in my thirties, hating my life, and his cancer made me re-evaluate it all.