Horror is the hottest genre in children's fiction, and Darren Shan's guesome stories sell by the millions. James Delingpole plucks up the courage to meet him

Darren Shan's home is a bit of a letdown. I've flown to his ancestral village in the west of Ireland fully expecting to find a sprawling pile (complete with dungeon) like the one inhabited by the magician uncle in his terrifying horror story, Lord Loss. Or, at the very least, a Georgian rectory befitting his status as one of the world's most prolific and successful children's authors.

'My books are never about violence and horror. They're about characters in extreme situations'Instead, the house is so very ordinary looking that I drive past it twice before I'm fully able to persuade myself that it really is the same one described in his directions. It's one of those modern, angular, character-free dormer bungalows such as you see dotted all over Ireland. Sure, it has a spectacular view of a lake from the rear garden, but it's scarcely consistent with the rags-to-riches conspicuous excess you might expect from a young literary multi-millionaire.

When I put this to Shan (born Darren O'Shaughnessy; 34; shortish with cropped dark and a roundish, boyish face; speaks with a strong London accent because that's where he grew up), he points out that houses in Ireland cost a lot more than you would think these days. And besides, he says, if he's going to spend money he would rather spend it on art. What sort of thing does he collect? 'Comic art. Impressionists.' Does he have anything good? 'Well, that one there,' he says, casually indicating an unremarkable rural scene on the wall above the fireplace. 'That's an early Van Gogh.'

Van Gogh! This is just the sort of twist Shan is so good at in his novels. He starts you out in a deceptively innocuous world of homework and football, boring history classes and unwelcome parental discipline, and you're thinking, 'Oh God. Another ruddy teen novel.' Then suddenly, the trapdoor opens and you're thigh-deep in pus and gore and the eviscerated corpses of people you were just getting to know and like.

Which is how Ivo, my seven-year-old and I, came to be such huge Darren Shan fans. On a friend's recommendation, we bought the first in his new Demonata series, Lord Loss, and began reading it as a bedtime story. Despite the mild hint of creepiness in the first chapter where the hero replaces his sister's towel with some dead rats while she has a shower, neither of us was remotely prepared for the horror in chapter two. (And if you don't know what happens, skip the next sentence.) The scene in which the boy's father, mother and sister are disembowelled and shredded by the demon Lord Loss and his vile familiars Artery and Vein, must surely be the most jaw-droppingly grisly in children's literature.

'If I'd had a serial killer rather than a demon doing those things, there would have been uproar''Oh, I don't like to boast,' laughs Shan, who thinks he gets away with it for two reasons. First, when you write in the realm of fantasy no one takes your horror too seriously ('If I'd had a serial killer rather than a demon doing all those things, there would have been uproar'). Second, his books may be 'dark', but they are also 'moral'. 'When the hero's family are wiped out, he doesn't just shrug his shoulders and go, "C'est la vie". He goes crazy. He has a breakdown,' says Shan. 'My books are never about violence and horror. They're about characters in extreme situations.'

Horror is the hottest genre in children's publishing at the moment. Shan's competitors include Nick Gifford ('Stephen King for kids'), Anthony McGowan ('The most disgusting book you'll ever read') and Anthony Horowitz, moonlighting from his Alex Rider books with a supernatural series, The Power Of Fire. Before them came R.L. Stine's Goosebumps and the Point Horror series. And before them came Roald Dahl, Struwwelpeter and the Brothers Grimm. Yet, for all the evidence that there are few things young readers enjoy more than being scared out of their wits, not one of the 20 children's publishers Shan approached in 1997 was interested in his first manuscript, Cirque Du Freak.

'Publishing is a business,' he declares, philosophically. 'It's not there to make writers feel good and publish their masterpieces and educate the masses. There had never been a book about a boy who becomes a vampire. Would teachers kick up a stink? Would bookstores not stock it? Would libraries not want it? I don't blame the publishers for turning it down.'

Of course, he can afford to be philosophical now. But he hasn't always felt this way. Born into a 'working middle class' Irish family (his mother teaches in a primary school, his father is a janitor), Shan had dreamed of being a writer since the age of 14. In his early twenties, after university, he had given up his day job working for a television company in Limerick ('very simple stuff: turning on and off people's Sky Sports, that kind of thing') to concentrate on writing full time.

'I was gutted,' he says, of the publishers' rejection. 'I was a young man on the dole and though I'd written books before, Cirque Du Freak was the first idea I'd had where I could see real potential.' In the course of a long miserable walk, he wondered whether he should get himself another job. 'Then I decided, "No! All those publishers are wrong. I'm just going to keep going with it." And events proved me right.'

To date, Shan's 12-part Cirque Du Freak series has sold more than 10 million copies around the world (he's especially big in Japan, where 98 per cent of his audience are girls aged between 14 and 30; he can't go to author events unescorted for fear of being mobbed), while the screen rights have been optioned for a 'seven-figure sum' by Universal Pictures. As Shan points out, these impressive-sounding movie-option deals are meaningless unless the film is actually made. But he's encouraged by the fact that the script is being developed by Brian Helgeland, the Oscar-nominated screenwriter of LA Confidential and Mystic River.

Despite his considerable fortune Shan lives a resolutely unflashy existence with his girlfriend, Helen (whom he met when she approached him to write something for the charity War Child). Like his hero Stephen King, he's determined to continue his Stakhanovite work rate no matter how rich he becomes: 'Nowadays, I've lots of money, but I still try to write as much as I ever did.'

Shan forces himself to write 10 pages a day (about 3,000 words), which will usually take him between three and four hours, after which he's free to surf the internet, watch films, go walking and answer fan mail. He doesn't much like the business of writing ('hard, lonely work: like doing homework'), although he does enjoy the creative process.

'People ask me where I get my ideas from, but everyone has ideas. A lot of writing's about posing the right questions: What happens next? How does he get there?' With Cirque du Freak, he always knew how it would start ('boy meets a vampire in a circus') and how it would end ('boy going reluctantly into the shadows to become his assistant'). All he needed to do was to fill in the gaps.

Shan specialised in children's literature during his English and sociology degree course at Roehampton, and is clued up on the mechanics of the genre. The key question, he says, is: how do you get the parents out of the way for the children to have adventures? 'So, in the Famous Five, the parents would be off on holiday, or they'd go and stay with their uncle. It's what kids want to read: children solving problems and facing dangers by themselves. They don't want mum and dad riding to the rescue.'

Because he writes in short, punchy sentences, Shan is much easier to read aloud than J.K. Rowling or Lemony Snickett (whose 'sluggish' style he can't stand). 'What I do well is plot,' he says. 'My books are like a roller-coaster ride, whereas J.K. Rowling's are more like a pleasure cruise, with a lot more enjoyment in the tiny details. Her imagination is amazing.' He also rates Anthony Horowitz and Eoin Colfer; though his favourite children's author is Philip Pullman.

Shan and J.K. Rowling share the same agent - Christopher Little - but Shan got there first, in the days when Little had never represented a children's author before. Oddly enough, Little's inexperience was partly responsible for getting Shan his big break. Determined to understand more about children's publishing, Little arranged meetings with all the people who had rejected Shan's first manuscript to find out where the writer was going wrong. On second reading, an editor at HarperCollins realised she did like the book after all.

'It's something I'm always saying to young authors: you need your lucky break,' says Shan. 'As a writer, you can push yourself as hard as you can, develop to the best of your ability, but without that lucky break there's nothing you can do. It seems crazy to think that J.K. Rowling or Stephen King ever needed a lucky break, but they did.'

 'Slawter', book three of 'The Demonata' series, by Darren Shan, will be published on June 1 (HarperCollins. £12.99) Pictures: John Reardon