In the week when the nation's attention was transfixed by a trial involving a baby, an au pair and a working mother, Dinah Hall found it salutary to talk to Penelope Leach, guru to a generation of British mothers. Her attitudes heightened for many the difficult dilemma of the working mother and left many feeling guilty. In the new edition of her book she has adjusted with the times.
Imagine one of the disciples interviewing Jesus, and you begin to get an idea of what it feels like to be sitting in Penelope Leach's kitchen.

As a journalist, of course, I should be doing a Judas and asking difficult questions, such as: "Whatever happened to maternal instinct?" and, "Are children like cars, that we need manuals to get them on the road?" But as one of the millions of mothers who spent the Eighties with a baby on one breast and Leach's bible of child care, Baby & Child, propped up on the other, my head resting on a metaphorical briefcase, I just want to throw myself at her feet and ask for absolution for parental failings.

This is really most unfair on Penelope Leach, who never set out to be dogmatic or authoritarian, but who has ever since had working mothers trying to offload their burdens of guilt on her. "What I can't understand," she says, "is that they tell me my book made them feel guilty, and then show me their copies, which are dog-eared, covered in coffee stains, breast milk and spit-up. And I say, if it made you feel like that, why didn't you bin it? You do rely on people to decide for themselves whether a book is useful to them or not. Disagreeing with it is a different matter, because disagreement must help you think out what you feel."

Leach has completely rewritten the book because she feels that the world has changed so much since she wrote it in 1977 - in terms of both parenting situations and new research - that working the occasional single father into the text would not have been enough. In 1977 the majority of mothers stayed at home, at least until their children were of school age. So a sentence like the following would ruffle no feathers: "A three-month- old baby," she wrote, "is ready to form a passionate and exclusive emotional tie with somebody, and you are elected." In the 1997 edition it is changed, significantly, to: "and, if you are the most central, loving person in his minute world, you are elected."

Although the title has been given a more cuddly Nineties possessive pronoun - Your Baby & Child - her basic philosophy remains unchanged. It is still unapologetically child-centred - a phrase that has dropped from favour in recent years, taking the blame not only for educational failings but also for the rise of that spectre of the Nineties, the "tyrannical" child. But Leach still firmly believes that getting it right for the child is often the same as getting it right for the parents. "After all, what's more disruptive than a whining, bored child?"

The Leach mother never has to feel guilty about following her instinct to cuddle and comfort. Leach also questioned the idea of a "spoilt" child. "It's not what you give them, but why. If you give them things and attention so that you can go to work, or take a bath, maybe that's `spoiling'. But if it's because you can't resist the expression on their faces when you give them a packet of stickers, or because it's a nice thing for a three- year-old to have ... You can be fortunate without being spoilt."

Leach was never explicitly anti-working mothers - she herself was one, though always part time. (She had the first of her two babies at the age of 28, once she had got her PhD in psychology - she was one of the first of the "elderly primagravidae".) But, inevitably, because she was able to put across so well exactly how babies and small children feel, any women with an ounce of empathy was going to feel miserable and guilty on reading about, for example, separation anxiety. And in the Eighties, working women were particularly sensitive about their position; the myth of superwoman was at its most potent and the woman who succeeded in her career was also determined to be a perfect mother. She was intelligent and literate, and it wasn't enough just to rely on maternal instinct: she wanted a more cerebral approach to childbearing, which is precisely why she was attracted to Leach in the first place.

Baby & Child was once aptly described by an American as a "PhD in child care"; Leach, a research psychologist, was highly qualified in the subject, but could also bring her own brand of empathy to it. Even now her descriptions of a baby's smile has me practically lactating. But all this knowledge had a price: would-be perfectionist mothers read the book and inevitably at some point felt let down by their own expectations.

"I can't apologise for this," says Leach. "It would be senseless to write a book about doing a job and not suggest we do it as well as possible. I'm not saying anyone who can't manage is a failure; on the contrary, nobody can manage to be a perfect parent all the time. But we should at least have a crack at it."

It will be interesting to see whether Leach will be able to bond with the new generation of mothers. Siobhan Peattie, policy research officer at the National Childbirth Trust, says that middle-class NCT members at least are still reading as avidly as they did in the Eighties, and that they tend to select books which "reinforce and reflect their parenting values", though NCT Maternity Sales have not stocked Leach's book for some time. Miriam Stoppard appears to be the frontrunner at present - possibly because she has such a high media profile - while Kitzinger still appeals to the more "alternative" mother, who wants to give birth at home. Miriam Stoppard's books may be easier to digest for a generation of parents weaned on daytime television, but Your Baby & Child is unapologetically literate. And if one is going to make classist assumptions about reading habits, does this mean she is reaching only a fairly middle-class audience, maybe even preaching to the converted?

"Yes, it's a lot of words," agrees Leach, "but I couldn't have done it any other way. It's gone so far the other way over the past 10 years - the Dorling Kindersley style of snippets of information. But I really, really don't see it as preaching. You won't be able to look something up in the index and find a statement that will `put you right' on it. It's about to what extent you feel the same side of the fence as your children - do as you would be done by. And I suppose, if that's preaching, then I'll have to take the fall for it."

One of the biggest changes in the years since Baby & Child was first published is the increase in day care. In the past Leach has criticised nursery care, particularly for small babies, for whom one stable care- giver is so important. But she is currently involved in a research project to assess the long-term effects of day care, and believes that in some families it may well be a valuable solution.

"I know of so-called stay-at-home mothers in America who spend the day on the golf course, leaving the children with au pairs. I wouldn't say that those children are getting more love and security than a child at a good nursery." One thing she is adamant about, though: a mother should always stay with a sick child. Asked whether she has any regrets about anything she did as a parent, she says she still feels guilty about going back to work too soon after her two-year-old had meningitis. And she is particularly alarmed about the American concept of "sick child day care"; they are opening up special wards in hospitals for children who are not well enough to go to their ordinary day care.

"Imagine - a sick child, being looked after by complete strangers. No, that's too much for me." We discuss how any mother could do this - though I can summon up half-a-dozen who wouldn't hesitate. But Leach is, as ever, reluctant to be too judgemental - she could see there would be times when a vital meeting at work might necessitate it. No, she could never have done it herself - "but then I found it very difficult to be a proper professional mother."

`Your Baby & Child' (Penguin, pounds 15.99)