You were a Goth when you were a teenager and you've written Gothic tales before. Had you wanted to write about vampires for a long time?

I'd wanted to write a vampire novel for ages but I was put off doing it because there were so many of them. You've got to find something original to do. I realised that the original thing to do, ironically, would be to go right back to the beginning to see where these legends started out before they became the Hollywood notion. So I found some American University Press books on Transylvanian and Romanian folklore.

You have to trawl through lots of really dull stories about sheep, and then you'll find something about vampires that's extraordinary.

'All I did was find all these extraordinary things, shift them slightly so they fitted my plot and then bolt them all together in a long line.'

I feel a bit of a cheat: all I did was find all these extraordinary things, shift them slightly so they fitted my plot and then bolt them all together in a long line.

So things like the episode with the thread was a slight reworking of a folktale about a beautiful widow who's being pestered every night by a figure and they attach a thing to it and they find that it's coming from the graveyard. How could you go wrong with something like that?

You're obviously very drawn to the winter landscape: snow features in The Book of Dead Days, My Swordhand is Singing and Blood Red, Snow White.

One theme I wanted to look at in Swordhand was that notion of it being winter - with a capital W - that defeated them. Although I set this in the 17th century, I was actually referring to earlier in the Middle Ages, when the Turks kept invading what is now Romania and there was one invasion where they were defeated.

It was a bit like the Napoleonic attack on Moscow, where they were more defeated by the weather in the winter than by the army that they were facing. So these Turks came storming into Romania and got caught up in a really heavy winter and went off and got lost in the woods and were never seen again.

You travelled to Romania to research the book. What did you do out there?

That was just a bit of geography, just for the colour. What I try and do in every book is go to the place it's supposed to be set, even if it's a mythical place, because you see things you can describe that you don't know what you're looking for until you see it.

If you want to research a specific point you can go to a library or do it online. It's only when you go somewhere that you can say 'oh, the trees are like this' or 'the mud is like this' or 'the sky is like that'. That really will help put some genuine colour into a book.

You used The Golden Bough, Sir James Fraser's classic work on folklore, for material about the Winter King and the Shadow Queen, didn't you?

I'm very lucky because I've got an original complete 13, 15 volume set of The Golden Bough. A lot of the pages are still uncut, so sometimes if you go to a page you have to cut it yourself.

'There's a bit in there on Transylvanian folklore and that's where the Shadow Queen comes from and that ritual of killing the evil thing.'

There's a bit in there on Transylvanian folklore and that's where the Shadow Queen comes from and that ritual of killing the evil thing. I just thought I'd make her more of a force.

The wedding of the dead is something they actually do in Romania. I made up the bit about going to live in a hut for 40 days because that seemed like an archetypal fairy tale thing to do. And also it helped my plot because I needed Agnes to get stuck out somewhere. But they really do do that.

The Miorita itself, the ballad, is the Romanian national song. There is argument about what exactly it means but it is supposed to be imbued with notions of how Romanians view themselves and their country and their nationhood.

So it's not exactly a national anthem but that's apparently how they feel about it. So I just took one interpretation of it and used it to sum up what I was really trying to say in this book, which is that it's okay to die. You need to accept that or you spend your whole life worrying about that and not living.

How did you find these various interpretations of the Miorita?

They were really hard to find. They were mostly online and in academic papers and blogs. You might find a student from America who was studying it or a Romanian professor who had written a bit about it. But I couldn't find a copy of it anywhere.

For the bits of the song I got the original Romanian and just got a dictionary and translated it and made my own version of it. It's basically Latin. The Romans invaded so the written language looks extraordinarily like Latin but with different endings.

You clearly enjoy the research.

I love history. I'm quite addicted to the researching thing. It's partly prevarication to put off writing the book, but also part of my process of making sure I've got enough in my head so when I get my time to write I'm not only thinking that I can write it, I'm actually desperate to put it on the paper so it happens quickly.