Once upon a time there were two talented young pupils in Derry Irvine's chambers. Both were members of the Labour Party in Hackney, both were on the look out for a parliamentary seat and each knew that, if their political career did not work out, there was still a good living to be made at the Bar.

One made it into Parliament, one became a successful barrister. And they might have lived happily ever after, except that one is certain to become leader of the Labour Party this week, and possibly the next Prime Minister. And that means the other will become fair game in a nation that still finds the sight of a woman getting on with her life curiously difficult to swallow. As Cherie Booth she has proved rather good at getting on. But will Cherie Blair be allowed to?

Consider the image-makers, for they fashion Heaven according to their fantasies. What could be more wholesome than the image of the church-going Tony Blair with his key asset - a happy marriage and three photogenic young children? It is caring and welldoing without being posh.

But look a little closer and the problem emerges: Mrs Blair is altogether too much her own woman. She has an unreasonable desire to protect her children from the acid spray of publicity and she seems intent on pursuing her well-established and lucrative career. The dread words Hillary Clinton have already been seen in print.

Cherie Booth has had some experience of difficult times with the press. Her father, the actor Tony Booth, best known for his role as the layabout Scouse son-in-law in Till Death Us Do Part, led a life of colourful and highly public debauchery. The fate of his daughters - Cherie and her six full and half sisters - appears rarely to have been uppermost in his mind as he generated tabloid headlines.

Tony Booth has belatedly become Cherie's champion, but when he published his autobiography in 1989, Cherie, her sister and their mother were simply not mentioned. Many other women were. In between frantic couplings, Mr Booth fought off boredom with two bankruptcies, several arrests and a close encounter with death by fire.

Under the circumstances, it was perhaps fortunate that he was largely physically absent from Cherie's life. She and her younger sister Lyndsey were brought up by their mother and paternal grandparents in Liverpool. Cherie was studious, clever and a high achiever. With four top-grade A-levels, she went on to a First in law at the London School of Economics and top marks in her year in the Bar exams. In 1976, she joined the Labour Party. No wonder Derry Irvine, the eminent barrister and a friend since student days of the late John Smith, was pleased to take her into his chambers.

No sooner had he welcomed Cherie when the young Tony Blair knocked on his door. 'I didn't want another pupil,' he said, 'but he talked so extremely fluently that I had to take him.' The rest, in romantic-novel style, is history. They met, they married. Derry Irvine made a speech at the wedding. Tony followed Cherie into the Labour Party; she fought and lost Thanet North in the 1983 election. He fought Sedgefield and won.

Cherie continued at the Bar, gave birth to three children and kept her Catholic faith. Tony carved his name on the Labour Party in the House of Commons. As a couple, they are hardworking, unpretentious and successful. What is it, then, as the political artillery finds its range, that we shall be invited to hate?

It has not been a prime feature of the British political tradition that wives are marketed either as assets or liabilities to the political careers of their husbands. In the present administration, they have chiefly starred as the pale, tight figures who are unhappily glued by the party machine to the side of a husband whose adultery has been exposed. Even the wives of past prime ministers have been noted mainly for the quality, or lack of it, of the table they kept. They have been, for the most part, figures in the shadows, their children all but anonymous, their function to suggest domestic stability and an absence of competition in the home.

But there have been enough exceptions to suggest that a trend might be detectable. When Neil Kinnock came under attack for abandoning the views that were previously the prime focus of criticism, the political thoughts of his wife, Glenys, were invoked darkly to suggest that Neil's trimming was not from the heart. When Margaret Thatcher resigned, the wives of the three candidates in the Conservative Party leadership race were drawn into the battle. And when John Major took that famous victory photocall on the steps of Downing Street, the image of Norma, round-shouldered and ill-dressed, trapped in the photographers' lights like a worried nocturnal animal, generated almost as much comment in the next day's newspapers as that of her husband.

Norma Major has since contrived an elegant double shuffle: she submitted to the make-over - the haircut and the clothes have been revamped and she has acquired a reserved poise on her rare public appearances. But her singular triumph has been to go missing. She has not moved into Downing Street and, apart from a few appearances in the last general election campaign - with the ubiquitous Jeffrey Archer as her minder - Norma Major has almost achieved anonymity.

Why is this blessed state unlikely to be accorded to Cherie Booth? Partly because she is that singular affront to male self-esteem: a high-earning, powerful personality and mother of three - and partly because she has a record of political engagement. And while the range of acceptable roles has widened in Britain over the past decade-and-a-half to accept that a woman can be as fierce a prime minister as the next man, the genuine dual career family, despite its prevalence in the real world, still feels like a balance that is out of balance. The image that Cherie Booth risks having thrust upon her is not that of the retiring Norma Major, but that of the emasculating, power-hungry liberated lawyer - Hillary Clinton. Cherie Booth, the Lady Macbeth of Islington.

What can she do? Her choices will be limited by the determination of her husband's political foes to render him unacceptable to the voters. The fact that the role of the Prime Minister's wife has never been a close match for that of First Lady will not prevent any sign of independent or intelligent thought in Cherie Booth being interpreted as a threat to the national constitution. She has, wisely, said very little so far and has generally succeeded in leaving for work before the reporters and photographers arrive at the door. She should grit her teeth with dignity at the coming jibes about the privileged middle classes who support the Labour Party but employ live-in domestic help: if she didn't have a nanny, they would accuse her of leaving the fate of her children to chance.

She should ensure that any nanny she employs signs a contract in blood prohibiting public disclosure of the family's business. And she should stick to her determination to follow her career. Politics is a risky business, and it did Margaret Thatcher no harm to have a husband who provided the financial security for her to pursue power. If Cherie can tough it out, she might become the first woman to pursue a successful non-political career out of No 10 Downing Street.

(Photograph omitted)