Rachel Billington's new book - her first venture into non-fiction - is called The Great Umbilical. It explores the relationship between mothers and daughters, which she imagines as a great matriarchal chain linking the generations; an unacknowledged DNA plait of love, shared experience and support in a hitherto patriarchal world. Her book examines a bond that, she believes, is due for rehabilitation: the three-sided relationship between mother, daughter and granddaughter.

Her theme is that women's knowledge, skills and tenderness are the vital elements in family life. They have been underestimated because a generation that valued equality above all else perceived them as feminine rather than feminist characteristics.

Any woman over 40 is likely to have had a domesticated mother who stayed at home to look after her family. Post-Sixties women, anxious to test their skills against men in the workplace, belittled 'mere' housewives, accusing them of being boring, limited, narrow-minded, dependent or submissive. Rachel Billington's book sets out to restore mutual respect between mothers and daughters.

Rachel herself stands at the mid-point of life. She has two grown-up daughters, Rose, who is 21, and Chloe, almost 18, and two younger sons; her own mother (Elizabeth Longford: biographer of, among others, Queen Victoria and the Duke of Wellington) is still alive. She is ideally placed to write about the complex web of love and resentment, dependence and competition that links mothers and daughters.

'Life runs backwards to your children and upwards to your mother, and though it can feel overwhelming it is above all exciting. I hated being an adolescent. I used to spend most of my time reading Victorian novels and wanting time to go faster. Nowadays I still think boredom and depression are the two worst things: perhaps because a lot of women of my mother's generation suffered from both.'

What sort of role model was her own mother, Lady Longford?

'She combined being a strong feminist, believing that her daughters were every bit as capable as her sons, with a strong sense that women had a different contribution to make to the family. These two apparent contradictions were resolved in her, which made her an easier mother to deal with than many others of my generation, for somebody who wanted to be both a feminist and a mother: although she did in fact give up her own ambitions as a politician because she wanted to put her family first.

'Women of my generation were determined to live a life that took in children and a career; and feminism made it possible. We're at a very interesting moment now, because the sexual politics of that dual life are to a large extent worked out. No mother today would try to prevent her daughter from having a career.'

Rachel Billington fervently protests when I tell her that the message which seeps between the lines of her book is that babies and small children need the constant presence of their mother, and that mothers have something close to a moral obligation to stay at home. But she concedes that reconciling the needs generated by babies and jobs is a problem nobody has yet solved.

'Occasionally the man can stay at home and share the burden, or the woman is lucky enough to be a writer who works from home, as I was; but even so, once you have more than one child, you're going to need help. I'm totally a feminist; but the first feminists didn't face up to the fact that you need a clan of women to help with child-rearing.'

Are men accepting more domestic responsibility? 'Yes, I think they are and will continue to do so. Men are discovering what a joy it can be to get closer to their children, and that's marvellous: they certainly shouldn't be kept away.'

When I suggest that her book implies that women who are not prepared to give up their careers should not have babies, again she disagrees. 'I think it's the right of every woman to have a child - indeed, as many as they want. I get upset when people say you should only have as many children as you can support. I think it's so much more important to create a child than anything else; but it's very easy for me to say, sitting here in my nice drawing room.'

Do her views stem from her Catholic beliefs? 'I'm not against birth control. On the other hand, I became a Catholic at the age of five and was educated in convent schools, so I have obviously imbibed a lot of doctrine.

'But as far as a woman's right to bear children is concerned, that probably owes more to my rebelliousness against authority. I hate anybody being told how to behave, particularly women, who have been so much at the whim of men. I hate the idea that anyone should tell women how to use their incredible gift of giving birth.'

It is true that Rachel Billington has many privileges: not that this deprives her of the right to state her views. Born into a family of eight children, she is the third of the Longfords' four daughters. Her husband is the film director Kevin Billington, and she enjoys both the support of a large family network (her eldest sister, Lady Antonia Fraser, lives just up the road) and the comfort of having enough money.

In her book, Rachel Billington quotes Margaret Drabble: a woman can manage a husband and work, work and children, or children and a husband, but never a husband, work and children. 'A most perspicacious remark,' she comments in her book. 'It is exactly that threefold commitment that a modern mother tries to handle. Whichever way she turns, there seems to be a responsibility waiting for attention.' Precisely. So what should the Woman Who Wants Everything do?

'First of all, I believe a mother has to take absolute responsibility for her child's welfare. In a natural, instinctive sense I feel that the buck stops with her. But that doesn't mean she has to spend every moment of her day with a small child. I see no reason why a secure, well looked-after child should not be apart from a working mother for part of the time, once it is weaned. But the woman who has a high-powered job is obviously going to find that threefold juggling very, very difficult. I don't go along with the American notion of 'quality time': I think young children need quantity time, too.

'It is a bit odd that feminism has so encouraged women to move out of the home that it has made caring for children seem almost politically incorrect. Feminism fought one very strong battle to get women out of their homes and into the market, but now mothers are getting a very bad deal: I wrote the book because they were being denigrated. The practical problems just haven't been addressed.'

They are not answered in Rachel Billington's book either; not least because there can be no one simple solution.

'I'm not saying that all mothers now must get back to the kitchen; but the mothering role needs far more support and praise from everyone: from the Government to other women.'

Rachel Billington's book is not just a straw in the wind. There is already quite a gale blowing. A former colleague, whom I visited recently to admire her toddler and new baby, assumed when she left work two years ago that she would return at the first opportunity. She has been amazed to find her two tiny children not only demanding but enthralling, too. She now plans to look after them herself for the next five years. Women now have the choice of whether to opt for home or workplace: and some are choosing full-time motherhood.

'The Great Umbilical' is published today by Hutchinson, price pounds 17.99.

(Photograph omitted)