There's a killer with a diamond dagger holed up in Coleford. Who is he? Katie Jarvis investigates...

Andrew Taylor doesn't look like a man who regularly kills people. Quietly spoken, well read, amusing; if anything, you might guess he was an Oxford don, specialising (perhaps you'd hypothesise) in Horace as an Epicurean (or some other such esoteric topic).

But appearances can be deceptive.

Say he were to invite you into his study - a book-lined hideaway tucked discreetly out of the centre of Coleford - and then left you to look around while he made coffee. You'd watch him walk over the courtyard to his 19th century cottage home next door, while you drummed your fingers for a moment on the desk where he writes. Then you might idly start browsing the packed shelves, which leave hardly a trace of wall on view: volumes of reference books, classics such as JG Farrell's The Siege of Krishnapur; poems by Catullus. (So far so good.)

But then, as you delve deeper beneath the respectability, a different - rather unsettling - picture slowly emerges. Unable to resist their aged spines, you lift certain of the remaining tomes off the shelves and there, between the pages, a shady underworld starts to form. Tumbling from the leaves land 18th century sots, befuddled by the suicidal pleasure of cheap gin; you're drawn into stinking slums, packed with filthy, starving children and their broken-down mothers. In another corner, murders are taking place - hangings, poisonings, shootings, knifings (and far worse, from which you avert your eyes): scenes from the ninth circle of hell.

You begin to feel jumpy - what is this sinister universe into which you've plunged? What does lie beneath the surface of this otherwise harmless-looking study? Suddenly, (you're not sure how; nothing has disturbed the silence), you notice the handle on the door slowly turning: the only door into the room. There's no escape...

And then the killer speaks. "Now you're doing what I always do," Andrew Taylor says, kindly. "Isn't it fascinating looking through other people's bookshelves?"

This is a man who has killed many times before and who is going to kill again. His victims range from illegitimate babies to sad spinsters. But, as always, it's his murderers who provide the real fascination. For the taboos that Andrew explores in his crime-fiction books (in case you hadn't guessed) go way beyond run-of-the-mill sex or nasty-way-to-die themes. Every one of his volumes provides a challenge to the very structure of our expectations: beautiful 'innocent' killers; murderers who cannot conveniently be filed under E for Evil. Indeed, his psychological perception and narrative skill this year secured him a to-die-for award: the Cartier Diamond Dagger for excellence in crime writing.

Don't think that all his victims are fictional, though. In his latest book, the unput-down-able Bleeding Heart Square, the victim is all-too-real.

"I was told about the Moat Farm murder of 1899 - a real Victorian case - by my grandmother," Andrew explains. "Her family were farmers near Saffron Walden. When her grandfather died in 1898, they sold one of their farms - Moat Farm near Clavering - to a man called Samuel Herbert Dougal. It was a very nice Georgian house, classical English stuff, with a moat around it, and he bought it with the money belonging to a woman who posed as his wife."

The story Andrew's grandmother spun for him when he was an eager 12-year-old, head stuffed with Agatha Christie and Sherlock Holmes, was later confirmed by one of those same research books that now fill his study. For it had gone on to become the subject of a celebrated Victorian murder trial.

"The woman's real name was Miss Holland: seven or eight years older than Dougal, with a little bit of money, poor lady. She was a sweet, gullible spinster and, basically, he seduced her; sucked her money out of her and shot her, before burying her in a ditch leading down to the moat. And then he led the life of Riley at the Moat Farm for four years; he hunted and shot; and he seduced the village maidens. And it was actually that that led to his downfall because there were so many paternity suits against him. At one point, he was having an affair simultaneously with a mother and her two daughters! Gradually, people began to ask a few questions about where the original Mrs Dougal had gone, and then they found the body."

Don't think that gives the story away; for Bleeding Heart Square takes the raw ingredients and transforms them into a dish far richer than the original. Its setting is changed, for a start: brought forward into the 1930s, against a background of raging fascism - fascism the book's main characters solidly oppose. It's a time of high unemployment, an economy in dire straits, a turbulent world...

"We've not quite airbrushed our fascism in the UK out of the records, but we don't actually make very much of it. Not nice to talk about it. Yet if you go back and read newspapers of the time, or memoirs, you realise just how big it was - certainly up until 1934 - and how respectable it was. It was very, very plausible. I've read some of Mosley's stuff and he was a shrewd communicator. He knew how to pull the right switches. Unlike the other fascist leaders, he had a very coherent economic philosophy as well - basically imperialism: we trade within the empire and keep everyone else out. We're a defensive unit against the world."

British jobs for British workers? Aren't there echoes bouncing round the walls today?

"Aren't there just! Very scary. At the time I was researching this, we had Iraq. There were even echoes there in the sense that, when the world is felt to be in a troubled state, people instinctively seize on what seems like an easy, simple solution - like George Bush's - and wade in. You simplify what is, in fact, an incredibly complex problem: Vote for us and everything will be fine! It certainly attracts people in the short term; in the long term, it leads to World War 2, as we know."

You can see, now, where all the research volumes come in: strange books he gets from the internet, from second-hand book shops, junk shops, friends. Books that look at ordinary life - lowlife even - between the important dates of history: journals, murder investigations, criminal trials. They're books that provide a window into the past, where so many of his novels are set. And he's meticulous to the nth degree.

"I think I carry research possibly to absurd lengths but I don't like cheating on history."

And that includes not only obvious facts and suitable language for a period in time - but even the specific zeitgeist, the morality: the very way people thought. This level of authenticity can prove a shock to modern sensibilities. Take domestic violence as an example. When Lydia (from Bleeding Heart Square) is beaten up by her well-to-do husband, she packs her bags and leaves her luxurious, servant-filled home for a cold, rented room shared with a father she barely knows. Even more significantly, her leaving home leads to ostracism by society: "Are you sure it's not just one of those things that marriages go through?" is her disapproving family's attitude to her plight.

"Domestic violence is a wonderful example of how things have changed," Andrew says. "Up until the middle of the 19th century, married women could not own property in their own name. The husband controlled them - almost owned the wife - and violence in the home wasn't something you had to apologise for - it just happened. If a woman left home, she lost her position, her respectability. It would be assumed she was wrong; that she was a sinner. And God knows what went on among the poor in very cramped settings."

He's spent untold hours immersed in letters and journals, lost within the times he replicates in his books. Certainly, many of the environments he recreates are vastly different from his own middle-class upbringing in East Anglia, the son of a clergyman headmaster. While not wealthy, it was undeniably sheltered and privileged: after boarding school in Suffolk, he read English at Cambridge.

"The real crunch came when I left university. My dad said, in the nicest possible way, 'When are you moving out, dear boy?' I said, 'Oh next week, I think!' And started frantically phoning around friends. Actually, being turfed out was exactly what I needed."

Although he'd had a vague idea he wanted to be a writer from the age of 12, the '70s were conspicuously lacking in creative writing courses ("the idea of which always makes me laugh anyway; as Malcolm Bradbury said, we teach children creative writing in our schools from the age of four"); so, while writing short stories and even the occasional poem ("God help us"), he drifted into working at his local library in an eclectic part of West London.

"You never quite knew what was going to come walking through the doors. Traditionally, the area had been Irish but, when I was there, that community had been overlaid by Asians and West Indians: very vibrant; very edgy. Most weekends, there was trouble on the streets. You had people coming through the doors of the library saying 'I've been raped; can you tell me what to do?' On the other hand, you also had the most lovely, gentle, gorgeous people in the world, who just wanted to read a quiet book or improve themselves."

Impressed by their employee, the local authority sent him to University College for a year to study librarianship. They achieved more than they could have hoped - though not necessarily in the way they expected. While he was there, Andrew spent most of his time immersed in medieval manuscripts. "I discovered the nub of what become the first novel, though I didn't know it at the time: Caroline Minuscule, which is the name of a medieval script. So it was a good year." (In other words, Brent Public Library played a modest part in catapulting Andrew into the top one percent of borrowed authors.)

It was during his year of study that he met his wife, Caroline, who has become instrumental in his success: a 'plot consultant', is one term he uses. It was she who persuaded him to give up work to become a full-time writer - on the thin promise of a �750 advance and vague promise of publication from Victor Gollancz. "Not a huge sum, even in those days."

Gamble it may have been, but it paid off. With Andrew's increasing success, they were able to move out of London to the Forest of Dean, where they've raised their two children, Sarah, 22, an artist and researcher, and Will, 19, who's studying sonic arts with a view to becoming a recording engineer. Success has followed success: Andrew's Roth Trilogy was filmed for television as Fallen Angel, starring Charles Dance and Emilia Fox. His books are now translated into multiple languages ("probably 12; 15 maybe"); and he's hailed as one of the country's leading writers: "sophisticated" (New York Times); "a master of psychological suspense" (Time Out); "exciting, readable and thoroughly amoral" (Daily Telegraph).

So what makes a great crime novelist?

"Luck."

Right...

"No, honestly. The longer I've been making my living as a writer - nearly 30 years now - the more I think it's all luck. Obviously, you need talent to some extent. To a far greater extent you need application, because writing is extremely hard work. But you also need luck; you see it sometimes with authors who are just in the right place at the right time. Once a certain sort of success comes, it seems to develop its own momentum, irrespective of the original kernel that set it going."

And why have crime novels become so popular, particularly in the last couple of decades?

"People read crime, partly, I think, for reassurance. In a crime novel, even the sort I write that are a bit grey around the edges, there's a resolution of some sort. Crime fiction does offer, by definition, to make a pattern out of the messy chaos of life.

"The other thing that crime fiction does, increasingly, is to describe and analyse what goes on around us; what goes on between men and women. More and more crime writers are using the genre, quite consciously, to do more and more sophisticated things; it's such an elastic format."

So should governments employ crime writers to sort out the justice system?

He laughs. "I doubt it. I certainly think a good crime writer ought to think a great deal about why people do things - why people commit crimes and how the consequences work, as well as the causes."

He cites as his formative influences a list that encompasses Conan Doyle, Samuel Beckett, Edgar Allan Poe (whose little-publicised period of schooling in England inspired The American Boy), and Noddy - underestimate that tinkling bell at your peril. "So many of us swallowed Enid Blyton up when we were young, at a time when we hadn't developed critical faculties at all. And so many of her stories are crime writ small, whether it's Noddy, Secret Seven or Famous Five. So is it any wonder that we're seeing such a wonderful flowering of crime writers in the UK? All Enid's fault.

"I have even heard it argued that The Faraway Tree is an interesting exercise in theoretical physics that prefigures a lot of what theoretical physicists are now saying."

But most of all, his influences are the ordinary people of life: the everyday diarists, the journal keepers, the criminals even, who've left their own stain on the silence. His next novel, The Anatomy of Ghosts (out 2010), draws on the scribblings of one Henry Gunning. "I found this," he says, waving a journal: "the reminiscences of a chap who lived in Cambridge; began as a student and ended up as an official of the university. An old man looking back on his youth, whose chatty, slightly gossipy memoirs call on his life in Cambridge during the late 18th to mid 19th century."

You can guarantee it will be a riveting read.

"There are some very clever crime writers out there," Andrew Taylor says. "They're labelled as genre crime writers, but they deserve to sit above the sauce at the great table of literature." He's not, as it happens, referring to himself. But he should be.

Bleeding Heart Square by Andrew Taylor, published by Penguin, is out in paperback, price �6.99