The latest book from the pen of Booker Prize winner Pat Barker is as dark, uncompromising and as firmly rooted in the North as its predecessors.

PAT Barker is great company. Witty and sharp, she tells a good story, occasionally makes me laugh out loud, which is somehow a bit of a surprise.

Her novels deal with the great dark themes of life - war, conflict, pain. She won the Booker Prize for The Ghost Road, the final volume of her First World War Regeneration Trilogy. Her latest novel, Double Vision, looks at the role of the war photographer and continues the story of Danny, a manipulative young man who killed an old woman when he was ten.

So it's a relief, really, to find that Pat is not the least bit grand or dour, but is warm, relaxed and thoroughly likeable - even when she's absolutely shattered, after a nasty virus on top of weeks publicising Double Vision.

"There are people who like the privacy of writing and those who like the publicity. I've yet to find anyone who enjoys both," she says, though she recounts with glee the story of being interviewed on American radio stations by people who not only had not read the books, but hadn't even read the blurb. "That's when you wonder why you're there..."

Despite the blackness of her themes - and they can be distinctly disturbing - her books remain essentially optimistic.

"They are about regeneration and redemption," she says, "Even Danny is not totally beyond hope. He's a gardener. He creates things. If someone can create things, there's always hope."

Pat was born in Thornaby. She never knew her father and when her mother married, Pat stayed with her grandparents and lived in Knaresborough and then back in Stockton in the rundown terraces that were the setting for Union Street, her first successful novel, which won the Fawcett Prize for fiction.

It was about as far from an Aga Saga as you could get. And no romanticised vision of working class life either. The women she wrote about lived harsh lives, coping with poverty, drunken men, wife beaters, abortion.

"But they weren't victims," says Pat. "There's no way in which those women were victims. They weren't defined by what happened to them, which was awful, but how they coped with it, which was amazing."

Having established herself successfully as a gritty Northern working class feminist writer, she then refused to stay in this nice neat pigeonhole, but instead plunged straight into the boys' own world of the First World War. Not in a gung-ho style, not even from the usual angle of the futility of war. Instead, she looked at the effects of shell shock seen through the character of Billy Prior, a working class, bisexual officer.

"And then feminist interviewers weren't happy because there weren't enough women in it," she says.

Now Pat is back into contemporary novels. If she had her life again, she says, she would like to study psychology. And it shows. She delights in delving into the darker recesses of human behaviour and reactions.

In Double Vision, Danny becomes Peter and tries to latch on to different people, almost looking for hosts to inhabit, stalking them, spying on them, copying their mannerisms, trying to be them. And leaving them empty.

"He's like a black hole," says Pat. "He creates this void which sucks everything into it. I'm always interested in people who go into that sort of caring work and make it their whole life. It makes them very vulnerable to people like Danny. People with nothing else in their lives have nothing with which to resist. They can be used, emptied almost."

Even sitting comfortably in the lounge of the Royal County Hotel, it's hard not to shiver.

Pat Barker is impossible to classify. Middle class, softly spoken, educated and articulate, yet she is still very much the product of her working class roots, and proud to be so. There is a toughness to her writing, a refusal to mince words or put things nicely, to avoid danger or shy away from the darker difficult topics, whether it's a vicar's feelings of aggression or a child's severed head on a Belgrade pavement. Life is as it is. Deal with it.

Her writing is easy to read, which belies the complexity of the thoughts beneath the surface. A major author, she is happy to keep out of the London literary scene.

And anyway she hates labels.

"What's the point of them? Putting a label on someone doesn't help, it marks them out."

Adam, the boy in Double Vision, has Asperger's Syndrome, a mild autistic disorder.

"Does it help to know that? Without the label, he might just be a strange child that people would accept and fit round. We used to have lots of people called cranks, who were nevertheless still part of society, accepted for what they were. Now they are all labelled but somehow not so easily accepted. Labels are always dismissive, putting other people into a ghetto."

Although she went to university in the south - history at London School of Economics - Pat never considered staying down there. "In any case, my grandmother, who brought me up, became ill. I had to come north to look after her."

She then met her husband David, a professor at Durham University. They live in Durham and have a son who's a gardener in Cheshire and a daughter, a journalist with The Journal in Newcastle.

Motherhood, says Pat, has been seriously devalued, the whole business of raising children turned into a modern minefield. "On the one hand we have ill-educated, neglected, almost feral, children. Then we have middle class children who are scarcely allowed out of the front door on their own. Something has gone wrong."

The Barkers are still very close to their children, "But now it's just us and three cats," says Pat. "How can I keep dashing off to London with three cats to feed at home?"

Her books are firmly rooted in the North. "A sense of place is important to me," she explains. After the Teesside terraces of Union Street, other books have been set in Newcastle. The latest is set mainly in rural Northumberland and on the coast, even the Farne Islands.

"I'm always aware of the North as a phenomenally beautiful place. I wanted to show more of it," says Pat.

In the book, though, this is a countryside recovering from the ravages of foot-and-mouth, where incomers have pushed up house prices and where the roads are full of squashed animals. Even the trip to the Farne Islands is in a thick sea fret and nearly ends in disaster.

"But that's what it was like when I did it," says Pat. "Even the conversation in the book between the other people in the boat actually happened."

For Double Vision she went to the war tribunals at The Hague and is full of admiration for the foreign corespondents' ability to make sense of it all, sum it up neatly for the next day's newspapers. "I couldn't do that at all. I was too busy noticing things like the shaving rash on Slobodan Milosevic's chin."

When she's not publicising books, or visiting war crime tribunals, Pat writes every day. "I'm sitting at my desk by 8.30am and aim to write 2,000 words a day, which is quite a decent amount."

It's reassuring to know that even she has an unpublished novel or two at the back of a drawer, "and enough rejections to paper a wall", she says cheerfully.

She is, she says, still unsure about her next novel. "Everyone's very keen on me to do a historical one again, and I might go back to before the First World War, but this time take a bigger swathe of time, a longer view."

The chances are that whenever it's set, it will be tough, challenging, and ultimately cheering. Just like its author.

* Double Vision by Pat Barker (Hamish Hamilton, £16.99)