"I don't think we'll miss you," Cherie Blair hissed to the waiting media scrum, as she finally left Downing Street last summer. From her first morning in No 10 – when photographers captured her scary hair and unflattering dressing gown – she scrapped with the media.
Her successor, Sarah Brown, already an accomplished public relations practitioner, was not going to make the same mistake of being branded a wicked witch with a letterbox mouth obsessed with New Age jollities. But after a year concealed in the shadows of No 10, Mrs Brown is making tentative steps into the limelight. And while her husband's image takes a daily pounding, Sarah is winning friends for shrugging off her near invisibility.
Unlike Samantha and David Cameron, she has kept her children, two young sons, strictly off limits for the prying hacks – even off Christmas cards – and her own rare public appearances have almost all been at Gordon's side; the loyal, silent wife.
No longer. On Monday, the "first lady" of British politics will host a glamorous A-list party in Downing Street to celebrate the 25th anniversary of London Fashion Week, which opens tomorrow. On Wednesday, she will be star guest at a celebrity bash hosted by Naomi Campbell, in aid of her favourite charity, the White Ribbon Alliance, which promotes women's health in the Third World.
Earlier this week, she was photographed with Campbell as part of the pre-publicity for fashion week, overcoming an understandable reluctance to appear in shot with exceptionally glamorous women. This was exacerbated by the "vile" press coverage she attracted after she appeared with Carla Bruni, wife of France's President Nicolas Sarkozy, when they visited Britain in March. "I didn't stand a chance, did I?" she said later. "I was standing next to a supermodel. Whatever I wore didn't matter."
She has also had a letter published in Elle magazine, and she kitted herself up in a smart white suit and elaborate floral brooch to be photographed for the October issue of Eve magazine, the cover story for which features Mrs Brown's friends Patsy Kensit and Davina McCall, chatting to her and other women about motherhood.
Just before the summer break, she also turned out for a book launch, and for a celebrity party held in aid of charity, for people she knew from her old days working in public relations.
Sarah Brown's friends – and Labour's spin-doctors – consider her emergence from the shadows long overdue. While her husband's popularity sinks, hers soars. Perhaps – some think – she is the means by which he could come across as a sympathetic human being struggling with an impossible task, rather than an obsessive technocrat buried in work. "She's a secret weapon, an untapped resource," says Kathy Lette, the Australian novelist who has known Mrs Brown for 20 years.
"She is an intellectual, but she doesn't wear pinstripe underpants. She is charming and disarming. She is more disarming than a United Nation peacekeeping force, and the Labour Party should unleash her."
There remains a nervousness within the upper echelons of the Labour Party about giving too much leash to a prime ministerial spouse. Cherie Blair was a successful and opinionated professional, a striking contrast to Norma Major, Audrey Callaghan, Mary Wilson, and all the other wives of prime ministers who accepted that their place was in the home, unseen and unheard.
Lance Price, who worked as a Downing Street spin-doctor during the Blair years, said yesterday: "Whatever people say about Cherie Blair, she identified very effectively the pressures there are on prime ministers' spouses and how difficult it is if you are an intelligent person with views of your own.
"It's unrealistic to expect all prime ministers' wives to be Norma Majors. Nor should they be; we need to get used to prime ministers being married to professional women who have their contributions to make.
"But the lesson from the Blair years is that they have to do it in a way that doesn't cause their spouse any embarrassment, no matter how frustrating that may be. So far, Sarah Brown has learnt that lesson fantastically."
Whereas Cherie Blair continued to practise law under the name Cherie Booth, Sarah Brown severed her link with Hobsbawm McCauley, the PR company she had founded with Julia Hobsbawm, and gave up her maiden name McCauley as soon as she married.
It is unlikely she would have made either sacrifice if her husband had been less of a public figure but he was already Chancellor of the Exchequer. Sarah Brown is perhaps the only bride in British history who knew she was marrying a future prime minister. She had ample opportunity to plan for the role.
All of her public activities since, other than her appearances at her husband's side, have been rigorously channelled into good causes in which she believes, and which have the additional advantage that they are not going to drag her into any embarrassing controversy.
Even in the feature in October's Eve magazine, which records a conversation in which eight women who know one another well talk about children and childbirth, it is notable that while seven give away small details about their family lives, Sarah Brown joins in only with observations such as "neo-natal units are amazing in terms of what they can do with little ones".
Inside her mind there is a full-time censor, barring remarks about anything controversial or revealing. Difficult for someone who can, as friends know, be great fun when relieved of the need to keep up her guard.
"She's a great girl," added Lette. "You can tell she is because she has got so many fantastic women friends. She has a sense of humour drier than the Priory. We have always got on, although we're very different. She tries to raise my tone while I try to lower hers."
The main cause she has taken up is organising help for women in the Third World so that they can give birth safely. "Every minute, somewhere in the world, a woman dies during childbirth," Mrs Brown wrote to Elle. "Despite all the progress in the past 20 years, this statistic has not changed since the mid-1980s." The White Ribbon Alliance, of which she is patron, bills itself as a "global campaign to save women's lives by investing in women's health".
"What I like about Sarah is she uses her position for good," Lette added. "The White Ribbon Alliance is one of her passions. She has lifted the profile enormously of that heinous crime against women."
The care that Sarah Brown has taken to avoid unwelcome publicity produced one unexpected setback when she arrived at the swanky members' club launch of a novel by the former gossip journalist Celia Walden, whose partner Piers Morgan is an old friend. The bouncer did not recognise her and, for one embarrassing moment, it looked as if she would be turned away as a suspected gate-crasher.
She took that with good humour, without trying the Don't-You-Know-Who-I-Am line, whereas Celia Walden is in no doubt that Cherie Blair would have reacted furiously if such a thing had happened to her. "Sarah is an extremely nice woman and very loyal," she said. "She hasn't put a foot wrong in any way and she's very savvy, so she is not likely to do anything like Cherie. People say if you could judge Gordon by his wife he would be fine."
Friends say that there is no political significance in her decision to emerge from self-imposed silence at a time when her husband's political future hangs by a thread. They say that it is simply that she is more at ease, having had a year to acclimatise herself to the restrictive life of a prime minister's wife.
But Tom Bower, Gordon Brown's very unauthorised biographer, takes a more cynical view. "Sarah Brown signed herself up right at the beginning to Project Gordon," he said. "She believes she has got to save her husband. She believes he lacks glamour, and she is trying to compensate. So we have a woman who has never shown the slightest interest in celebrities suddenly putting herself around all these people. It's sad and desperate."