Interview: Rose Tremain, the Orange Prize winning author on her new novel 'Trespass'

• Rose Tremain

"I wanted to write about how people try to make sense of the last third of their lives," Tremain says . "Life after 60, which is where I am. You don't know how much longer you've got. You start to look back and see the shape of your whole life. It sounds depressing, but it's important."

We're in the south-facing parlour of Tremain's splendid Regency home in Norfolk. The house rests on top of a hill, regally presiding over Norwich. Tremain has lived here since 1985, for much of that time with the biographer Richard Holmes, whom she met on a flight to Australia in 1992. She was twice divorced, had resigned herself to remaining alone, and promptly fell in love with him. "It's a sustaining relationship, a wonderful ongoing conversation," she says.

"We're tremendously good companions and he's a very kind man. Kindness is important and in short supply in this world. Having lived with two rather angry people I do appreciate it. I'm very fortunate ..." she pauses and checks herself. "Well, I think we both are."

It's an idyllic set-up. Holmes writes upstairs, she taps away in her bright little study off the parlour. They meet for breakfast and dinner every day. Summers are spent in France, in their house on the edge of the Cevennes, and they have a London flat.

Tremain comes across as very contented, much more than her menagerie of struggling, searching characters, though she admits her books are exploring darker territory. "That happens when you get older," she says. "But my favourite mode of writing has always been black humour. You needn't infer that my life has become bleak."

Tremain is self-possessed and formidable, constantly fixing me with her stare and looking me up and down. She has a sharp sense of humour and I get the impression that away from the business of doing interviews she would relax and be great fun. She is also very thoughtful, insisting on paying for my taxi to Norwich and constantly asking if I'm comfortable.

Elegance is a word that springs to mind. It sums up the palette and period furniture of her home, the books stacked neatly on every dusted surface, the sugar cubes on our saucers, everything just-so. It describes the rolling landscaped gardens you can see out of the grand windows, each lawn made a dropped handkerchief by the snow.

It characterises the 66-year-old woman perched on the sofa, make-up meticulously applied, hair neatly dyed, looking a decade younger than her years. And elegance also describes her clipped, cultivated and clever prose that has seen her published in 27 countries and counting. "A true stylist," is how Tremain's peer and friend Ian McEwan describes her. "Rose is a writer who cares about her novels at the level of the sentence."

Writing has always sustained her. "I was reading about the life of Jean Rhys the other day and she came to this realisation that the thing that made her happy, that gave her some equilibrium and peace, was writing," Tremain says. "But she came to it too late, in her seventies. I thought about how fortunate I am. I understood that very early on. I knew what made me more happy than anything was writing. It had always been so for me."

Trespass tells the story of two sets of siblings, one English, one French, all of them haunted by their pasts and connected by an isolated stone farmhouse in the Cevennes.

In some ways it's a cleverly plotted whodunit, with all the red herrings and characters behaving suspiciously that you might expect. But the murder isn't really the pivot on which the story turns though Trespass was inspired by a moment of terror.

"You're too young to have seen Le Boucher by Claude Chabrol," Tremain says. "It's a devastatingly good film, quite horrendous." Trespass begins with a homage to a scene from that film, about a serial killer in a small French village. "A teacher takes her kids on a picnic," Tremain continues.

"There is an overhanging cliff, a close-up of a girl's hand on a baguette, and blood starts to drip on to it. I wanted to find in my book a moment of terror as powerful as that. My working title, which my New York agent said was pulpy and camp, was Blood Sandwich."

This is how stories come to Tremain, via visceral images that arrest her for the two years it takes to conceive and write a novel. She has no interest in her own biography, which is why Trespass is so wildly different to The Road Home, about an Eastern European immigrant arriving in contemporary London, which won her the Orange.

She is interested in other people, not herself, and is conspicuously absent from her own canon. Her editor of more than 30 years, Penny Hoare, said Tremain's first manuscript thrilled her because, "It was so unlike most people's first novels, in the sense that it didn't seem to be in the least bit autobiographical."

"Writing for me is like going on a journey," Tremain says. "It's not this old idea of writing what you know. Sure, my own experiences are in the books. My own character is in there disguised and displaced. But I'm not interested in exploring my own biography in fiction.

I'm not afraid of it. I just don't find it compelling." This is why she never runs out of steam. "If you write from your life you use up the family silver," she says. "My life is virgin; I haven't touched it and I probably never will. And I think we've had enough memoirs, don't you?"

The closest she came was toying with the idea of writing about her mother. "She died in 2002 and out of affection for her I thought about trying to resurrect her early life," says Tremain. "She was the middle child and the two others died, one at 16 and one in the war. My grandparents were left with the child they didn't love, which was heartbreaking for them and for my mother. She saw herself in quite a profound way as unloveable, which made her, of course, at times very difficult. Then why didn't I do it? I didn't want to."

What Tremain's books have in common, apart from their difference, is her feeling for oblique and outsider perspectives. She is a very compassionate storyteller, whether assuming the identity of a courtly rogue in Restoration England, the Duchess of Windsor, a transexual, or a modern day immigrant. Tremain often receives letters from fans who are in love with her characters and speak of them as though they were real. Still, the fact that she is impossible to pigeonhole has exasperated many a publisher. "They're starting to talk about it as a strength," she says, raising an eyebrow as if to say, "Finally!".

"People don't get bored of my fiction because they never know what they're going to get."

Most of Tremain's books, going right back to her breakthrough, the Booker-nominated Restoration, were written in this house, first on a secondhand typewriter she bought for 8, these days on an old PC that looks as if it's well into the last third of its life. She shows me her study towards the end of our interview and it's a cheerful, cosy space with a globe on the desk and photos of her mother and daughter, a psychotherapist in London, on the wall. "My daughter just said, 'Mum, your study is a tip, so I've tidied it'," she says, though nothing about Tremain, from her prose to her thinly plucked eyebrows, is untidy. "I'm very attached to it. It's significant for women, the room of one's own, don't you think?"

Alongside McEwan, Martin Amis and Kazuo Ishiguro, Tremain appeared on Granta's first list of leading Young British Novelists in 1983. Unlike them, however, she had to wait more than two decades to win a major prize, despite being nominated almost as much as Beryl Bainbridge. I think Tremain still thinks she doesn't get the recognition she deserves, though she is too polite to say it. She is, however, refreshingly lacking in modesty when she talks about finally winning the Orange Prize. "It felt rather like a relief to win a major prize," she says. "People are rude about the Orange and say it excludes men. Well, all prizes exclude someone. The Booker excludes Americans. I was delighted to win it." Did it feel like a vindication, I ask, noting that it took a long time. "It sure did," she laughs. "I mean the last time I was nominated for the Booker was in 1989. That's 21 years!" Her eyebrow heads north again before she delivers her supremely elegant last word on the matter. "I have been quite patient with regard to those prizes."

Trespass is published by Chatto & Windus on 4 March, priced 17.99.