Like the Royals before them, the Blairs now carry the weight of a nation's expectation says Natasha Walter

IMAGINE YOU are Cherie Booth. Imagine that you thought you had finished having children, with three kids aged 15, 14 and 11, and then you found out, at the age of 45, that you were pregnant again. Shock, laughter, joy, fear - what a riot of emotions you might feel. And then comes the day when you wake up and have to look at yourself beaming from the front page of every newspaper in Britain. Because your baby is not just a turning point for you and your family; it is a media event. That is the reality for the Blairs and their new baby. Already, however private they might have wanted to be about it, the pregnancy is not just part of their family life, but also of the life of the country.

IMAGINE YOU are Cherie Booth. Imagine that you thought you had finished having children, with three kids aged 15, 14 and 11, and then you found out, at the age of 45, that you were pregnant again. Shock, laughter, joy, fear - what a riot of emotions you might feel. And then comes the day when you wake up and have to look at yourself beaming from the front page of every newspaper in Britain. Because your baby is not just a turning point for you and your family; it is a media event. That is the reality for the Blairs and their new baby. Already, however private they might have wanted to be about it, the pregnancy is not just part of their family life, but also of the life of the country.

That will be even clearer when the baby is born. Alastair Campbell must have been delighted when he heard the news. Now he can look forward to a delicious photo-opportunity at a crunch time for Tony Blair. May 2000 might have been expected to be the time when the fortunes of New Labour would be hitting the doldrums, with class sizes not yet small enough, waiting lists not yet short enough, the Dome looking tired, and the elections for London's mayor giving naughty Ken a constant platform. But now there will be something to take the minds of the electorate away from homelessness and crumbling railways. A lovely picture of a lovely family with a lovely new baby to complete the look of innocence and hope. You are right, Alastair, it is a pretty picture for the new millennium.

And if even trivia such as Cherie's wardrobe, or where the Blairs go on holiday, or what their favourite food is, can command endless column inches, how much more fascinating a new baby will be.The media do not just want a prime minister who gets on with the job. We also seem to want a figurehead who will reflect back to us something about our private lives, our holidaying and eating and dressing habits, and our family lives.

The Blairs are gradually being invested with the same kind of significance that the media traditionally gave to royalty: they are watched and written about not just for what they do, but for what they are. In the United States, presidents have been used to that sort of quasi-royal status for a long time; some of the most powerful images of John F Kennedy's presidency were those of Jackie and John Junior at home in the White House. The family scenes gave Kennedy an aura of youth and compassion as well as power, and ever since then Western political leaders have been painfully aware of the need to appeal to voters on more than their political competence.

Given this obsession with politicians' private lives, the glow that is cast by the expectation of a new child will work in the Blairs' favour. Usually, it is hard for Cherie to get things right: even women who want to like her feel baffled by her acquiescence in accompanying her husband smilingly and silently to public functions where she has no role to play except that of clothes horse and little wife. Earlier this week, Cherie was definitely out of favour. Every national newspaper in Britain was running articles picking over her wardrobe after a "friend" told newspapers she was feeling the pinch because her clothes cost so much. All the journalists were happy to criticise the amount of money she spent on her shoes or her suits or her hairdresser, and her penchant for long jackets or fussy necklines or shiny fabrics.

But now, everyone loves Cherie again. The Daily Mail commented approvingly: "Cherie is very much a woman of our time." The Telegraph allowed that "the Blairs have always stressed the importance, both personally and for Britain, of a sound family environment". William and Ffion Hague were quick to send their congratulations. The new baby enhances Cherie's status, not just as the Prime Minister's wife, but as a role model. Because although her life may be anything but ordinary, as a working woman with children she embodies a pressing dilemma of our time. Women are always mocked for saying they want to have it all, but who wants to settle for less? How can we do it? Will our children suffer? Will our jobs suffer? Will our relationships suffer? There are millions of women who are already trying to answer those questions, often in truly difficult circumstances. And in Cherie Booth's admittedly charmed life, they can see an echo of what they are living through.

But that does not mean the media will give her an easy time throughout the pregnancy and the following months and years. At some point, the carping will start. What will Cherie Booth be criticised for? Working when she has a tiny baby and so encouraging women to desert their children, perhaps. Or not working for a while and so encouraging women to drop their jobs. Sharing the childcare with her husband and so making him unable to concentrate on state business, maybe. Or not sharing the childcare with her husband and so retreating into the role of a little wifey. The media certainly will not be able to resist scrutinising and criticising her arrangements.

At some point, one hopes that the spotlight that is being trained on Cherie Booth over this pregnancy will shift to her husband. After all, he has promoted himself to the public as a family man as well as a prime minister: he thrives on the intimate style of contemporary media. He does party political broadcasts sitting in his kitchen, he talks about his children in interviews, he sets up photo-opportunities with his family on the steps of Downing Street or on holiday. He has actively presented himself as a new man to the electorate: "The first thing I think about in the morning is whether Kathryn's nappy needs changing," he told a newspaper ten years ago. His friends tell reporters that he is happy to look after the three children on his own, and he says he would rather spend a weekend with the kids than at a meeting of Commonwealth heads of state. And, of course, he likes to tell the rest of us how to manage our own families, by calling for a "new moral purpose" in Britain where children should be kept under control and families should stick together.

If he wants to go on projecting this image of a modern father, then he has got some real choices to make. Next month, the legislation that enshrines the right of fathers to take three months' unpaid parental leave comes into force. I was sitting at the Women Lawyers' Forum earlier this year when Cherie Booth raised her hand to signal that she was in favour of the motion that this leave should be paid. Clearly, she thinks that fathers should be encouraged to take time out of work to care for their young children. And why not? Gordon Brown or Mo Mowlam could do a very good job as temporary prime minister for three months next summer. It is not very likely that Tony Blair could bear to give up the reins of power for a moment, let alone three months. But if he really wanted to prove himself, both as a good father and as a role model for a new Britain, that is what he would do.