WELL, would you swap bodies with a member of the opposite sex? How would you feel if you, as a woman, suddenly found your soul in the body of a man? Or vice versa?

That's what happens in Mantrapped, the new novel by Fay Weldon, who is appearing at Poole Book Word and Book Festival on Monday (Oct 11).

The traps of relationships have been a recurring theme in the novels of Fay Weldon, who now lives in Dorset and, once again, has broken new ground by creating a publication that is part fiction and part memoir.

As in her acclaimed autobiographical book, Auto da Fay, it touches on tender subjects. This time, for example, she reflects with honesty on breaking up from her husband of 30 years - he died on the day the divorce came through - and on once having an abortion which was "to make the whole family survive", she recently explained.

"Mantrapped is a kind of hybrid novel, my theory being that fiction alone is not enough," she told me. "The internet has changed everything; it is no use writing books as if it was 50 years ago because people know everything about the writer already.

" It seems rather odd nowadays to keep yourself out of your novel, and so this is a mixture of memoir and fiction that are not really connected, except subliminally."

The story part is about two characters called Trisha and Peter who brush past each other on the stairs and instantly swap souls. Peter finds himself inside Trisha's older body and Trisha in Peter's.

An odd concept, albeit it a fascinating one, but the story of Fay's own life has also been far from ordinary.

Where do you start? Scandal touched her family, thanks to her grandfather's free love advocacy, before she was even born. And an aunt, having slept with an older relative when still a girl, ended up locked away in an asylum.

As a young child Fay emigrated to New Zealand with her doctor father and mother, who subsequently split up.

After struggling for years to get by, her mother - "the person I most admire", she told me - managed to return to England with her two daughters and Fay was never to see her philandering father again.

Auto da Fay told the story of a gutsy, practical, clever lady with a strong capacity to surprise, who made it to St Andrew's University, became a devoted single mother in the days when it was still heavily frowned upon, and married an eccentric headmaster, partly "to have a roof over my head".

It was an odd marriage that her then husband had entered to help further his career, she suggested, and it was a sexless one.

With that husband's encouragement she became a night-club hostess and also had sex with other men.

In Auto da Fay she distanced herself by writing in the third person about this uncomfortable time. How does she feel today about that celibate first husband who wanted to know all about her experiences with other men?

"He was really good to me. I feel really bad about portraying his little ways in Auto da Fay, but in this second version I am just as bad.

"I could always have not gone and worked in a night-club but it did not occur to me not to. You can only conclude I rather wanted to."

In the end, after being attacked by a man with a knife because she shunned his advances, she voted with her feet, as they say, to change her life and became a runaway wife.

Grittily, she managed to bring up her son while pursuing a career writing adverts, including the classics "Unzip a banana" and "Go to work on an egg", as well as the sadly unused "Vodka makes you drunker quicker".

Then, one evening in the early 1960s, she went to a London party and set eyes on an artist from Bournemouth. Which is, more or less, where Auto da Fay ended.

Now the reflections of Fay Weldon in Mantrapped move the clock on to the years between 1963 to 1975, giving insights into a woman who was trapped by love.

"The story continues, as it were," said Fay. "It takes another look at those characters and it is odd that if you write about them at a different time the perspective you have on them changes."

Throughout her writings, the author- who has been both at the forefront of feminist writing and yet once upset some with a remark that rape, though monstrous, was "not the worst thing that can happen to a woman" - has chronicled the changing woes of relationships and her latest gender-swapping story continues to ask piercing questions.

So have men changed over the decades? "Oh completely," she replied. "Men are much nicer than they ever were." (Phew, I thought. )

"Men were all-powerful, while women had no power at all unless they had private incomes and lived out of courtesy of men.

"Men had power and power corrupts and they behaved rather badly. In these days I think women have most of the power and can behave appallingly.

"The dominant role is held by women. They occupy the moral high ground. Even if the wage gap is still there, it is only because women have children and choose to give more time to them than to a job.

"You don't have to have children. It is not gender that is at fault."

Fay Weldon, just 73, is a woman who has often confronted the controversial and she recognises patterns in life. "You get the sense of destiny, if you like, of fate falling out in certain ways."

So it was with the meeting of her second husband, Ron Weldon at that Primrose Hill party in the early 1960s.

"It was love at first sight. You just look at someone and think, 'That's the one.' You have this extraordinary feeling of fate that many women report and I don't know what it is. It is the voice of future children calling."

Ron hailed from Bournemouth. "His family lived in a big house by Holdenhurst Road that backed on to the golf course. There was even a Weldon Cup at that golf course and, I think, there still is.

"Again, the father had left the mother and she was left in Bournemouth. Ron went to prep school there and he went to Bournemouth Art College, which, in those days, was a very remarkable place. He played trumpet and he set up a jazz club in Bournemouth, which was rather rare in those days."

Her life with Ron was a lively one, often rubbing shoulders with celebrities as Kingsley Amis, Sylvia Plath, Ted Hughes and George Melly.

They had three children, three more boys, all "born in love".

Fay and Ron had 30 years together which was "longer than we deserved and longer than is granted to most, and for that I must be grateful," she wrote in that first autobiography.

Destiny, however, once more played a mean hand and eventually they parted.

"We divorced and he died and I thought the world would end."

It didn't, of course. Today Fay Weldon has happily re-married and she and husband Nick Fox live in Shaftesbury.

Among her activities she is president of the Friends of Guys Marsh, the charity that helps families and visitors to the prison. She is also keen reader of sci-fi.

"Some are very, very good, like Iain Bankes, and I was always a great fan of Philip K Dick. If you read things that were written even 20 years ago, it is all true now," she said. "It is hard for sci-fi to keep ahead."

And by her bedside? "I have piles and piles of books, mostly bought by my husband at church fetes, and mostly from the libraries of retired generals. I read an amazing number of books on subjects like the Siege of Singapore, the Fall of Constantinople or Spycatcher.

"It is a voice from the past, a different kind of voice and somehow courageous, responsible and male."

By contrast, her office is full of contemporary fiction for she is a much-sought after judge of prestigious literary awards. "They are two very different worlds," she added.

Today, a church-going Anglican ("other religions are based on the necessity of absolute belief and literalism that does not suit people like me"), she has been called assertive by critics, but she's an optimist whose infectious laugh is never far away.

"I see myself as hopeless and vague but then you never know yourself, do you? People who go to self-assertion classes can often be people who are assertive to the point of mania.

"But they believe they are unassertive. How does one know oneself?

"I was in hospital the other day, giving an account of my symptoms," she laughed. "The doctor turned to me and said: 'You know you are completely mad'.

"And these were not even mental symptoms! They ask me what something feels like and so I give them similes they are not accustomed to!"

And (well you have to ask, don't you?) if she were stranded on that Desert Island what book would she take with her?

"I'd go for blank pages and a pen and write my own," she teasingly asserts.

And one last thing - if she had the opportunity to swap her soul for a man's, would she do it?

"No I wouldn't," she said, firmly. "Certainly not now. Twenty or 30 years ago I think I would. As well as soul you would have would have had this amazing sense of male power, dominance, freedom, the capacity to concentrate ... but I don't think that's there in the male very much any more.

"Women have it much better and so although women are plagued by guilt and anxiety and always will be, I suspect, these days I would, rather have that kind of complexity."

So don't cross her on the stairs.

Fay Weldon's new novel Mantrapped is published by Fourth Estate at £16.99: She will be talking about Mantrapped at Poole Lighthouse (tel. 685222) at 7.30pm on Monday October 11 (£7.50 with concessions for Access to Leisure).

The BBC TV version of her novel The Life and Loves of a She-Devil is now available on DVD at £19.99 published by Network.