I talk to children in schools all over the world, and I've found that both boys and girls are fascinated by how hunter-gatherers manage to survive entirely on what's around them in their environment: trees, rocks, animals and plants.
To experience the northern forest in the raw, I went to northern Finland and Lapland, travelling on horseback, and sleeping on reindeer skins in the traditional open-fronted Finnish laavu. I ate elk heart, reindeer and lingonberries, and tried out spruce resin: the chewing gum of the Stone Age.
If you get a sense that your writing isn't quite working, change it. Or cut it out. Don't just tell yourself it'll do, because it won't.
I definitely don't write with any kind of 'message' or 'lesson,' probably because when I was a child, I used to run a mile from books like that.
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.
In general, when I'm writing, I concentrate on the story itself, and I leave it to other people, such as agents and publishers, to work out who it's for.
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.
In a ghost story, usually you've got to hang on until daylight, and you'll be alright. But if daylight's four months away, then you have a problem.
The most remote place I've been to was in Greenland. I remember setting out for a solo hike from a small cabin, itself several hours' boat ride from the nearest settlement.
My novel 'Wolf Brother' is set in northern Scandinavia during the late Stone Age, so I was aware from the start of Norse influences. I used some Norse names, and the soul-eater Thiazzi is based on the Norse storm giant, Thiassi.
I would love to live in the wilds of nowhere, and when writing 'Chronicles,' I would occasionally rent a cottage in the middle of nowhere that had no mobile reception, but I'm not about to move away from my family.
Why do so many children love the idea of being snowed in or shipwrecked, of having to survive on one's own? When I was a child, I was no exception. I wanted to hunt with a bow and arrow like the Stone Age people: to skin deer and build my own shelter. And I desperately wanted a wolf. As we lived in London, my options were limited.
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.
For me, inspiration isn't a sort of spark which lights the fire of the story. It's more like a thread, one of many, which you can tease out of a story once it's written, if you feel so inclined.