She may dislike the term Aga saga, and the current government, but, as Brian Viner finds out, Joanna Trollope's tales of human experience are set against a background that could only be England.

TALL, slim, attractive, wealthy, fiercely intelligent, beautifully tailored, deliciously posh, impeccably well-mannered and with an emotional hinterland worth exploring, 61-year-old Joanna Trollope - who lives in London during the week and, at weekends, holes up in her Gloucestershire cottage with her beloved labrador, Max - could almost be a character in one of her own bestselling novels. Which are emphatically not "'Aga sagas' - an expression she dislikes intensely.

Agas feature in only two of her 12 novels, she points out. And only three are set in villages.

So her reputation as a chronicler of village life as it unfolds around the Aga hotplate is as undeserved as it is unwanted.

What her novels are, are carefully researched stories often revolving around seismic family upheavals, in a contemporary middle-class setting.

Her latest subject, in Brother and Sister (just out in paperback), is adoption. It is about the search by two adopted thirtysomething siblings for their respective birth mothers, and the emotional fallout that follows.

In researching the book Trollope talked to lots of people, both men and women, who had been adopted as children.

"These are tremendous generalisations, but in the men, there seemed to be a slight mistrust of the feminine," she says. "And one man spoke, very articulately, about problems with intimacy.

"Apart from the novel I wrote about step-families Other People's Children, I don't think I have ever met people who wanted to talk so much," Trollope continues.

"And the only one in such raw territory as this was Next of Kin, for which I interviewed wives of farmers who'd committed suicide. This was just as visceral."

Her own childhood was not without its complications. A great-niece several times over of the novelist Anthony Trollope, she was born in 1943, but did not see her father until 1947, when he returned from India. She has a brother five years younger - a leading QC - and a sister eight years younger. Their mother is 85 and still in marvellous fettle. Indeed, when a few years ago Trollope's name was splashed all over the tabloids following the entirely erroneous story that she trawled the streets of London looking for younger men, the old lady dealt marvellously with the journalists doorstepping her for tittle-tattle.

"She told them, 'If I had anything to say about my daughter, the last people I would share it with would be rubbish like you'."

While she was enduring what she refers to as "the beastliness", Trollope was contacted by the late Lynda Lee-Potter, asking for an interview.

"I said to her, 'Do you know why it is, why I am on the receiving end of such extraordinary viciousness, much of it from girls I've never met who are younger than my own daughters? And Lynda Lee-Potter said, "One reason, darling: you're too thin."

I laugh, while acknowledging the pain she must have suffered. It is a British trait, I venture, hurling abuse at the rich and famous. "There is certainly a very British discomfort with female success," says Trollope, and in particular middle-aged, middle-class female success.

I ask her: is it a burden to be labelled a middle-class writer?

"It's tiresome. People are required to be so apologetic about being middle-class. If they find an ancestor who went down a mine, it's such a relief to them, yet that kind of behaviour is just as pretentious and snobbish as sounding like I do is perceived to be."

Not everything about her is as it seems. For example, I have her down, wrongly, as a staunch Conservative. "I voted Tory once, but every other time I have voted Labour or Liberal. This time I'm not sure. I voted for Labour in 1997, but I find this an interfering, patronising government, and I think what happened to Blair is vanity."

Disgruntled as she is with the government, Trollope thinks this a much kinder society than the one in which she grew up. "Oh, infinitely so," she says. "Whatever anyone says about violence, sloppiness, exploitation, these are much more humane times than the narrow-minded world in which I grew up."

That narrow-mindedness dictated that women were expected to marry young, and then have babies. She did precisely what was expected of her, marrying at 22 and conceiving fairly soon afterwards.

She has been married twice, with two daughters from her first marriage, and two stepsons from her second, to the playwright Ian Curteis.

The acrimonious end of that relationship in 1998 knocked her for six. But she can talk about it rationally now.

"I have had a couple of relationships in the past six years, and when it happens it's a lovely add-on, but romance is not a major preoccupation for me any more, and that's rather liberating. What stops being a preoccupation is the feeling that one becomes invalidated if one is not in a relationship, that one is somehow diminished."

It's hard to imagine Trollope ever feeling diminished or invalidated, although she insists that there have been times when she has. She finds validity now not only as a supremely successful novelist, but also as a doting grandmother of three.

"Grandchildren are a luxury, emotionally. We can indulge them. Having said that, I do want to be the kind of grandmother whose existence is ordinary."

Just as she combines London and Gloucestershire, so she combines grandmotherhood and the life of a footloose singleton.

"I live a perfectly brilliant dual life, she says. "I'm enjoying the freedom that girls in their twenties and thirties have, just a bit later. But as one gets older, one also realises that people take precedence over everything. It would be wonderful to see the Great Wall of China, but it is not in the same category of urgency as seeing one's family and friends."

* A fuller version of this interviw appears in this month's Sainsbury's magazine * Brother and Sister is published in paperback by Black Swan, priced £6.99.