One of two fates tends to await the pop star whose star is no longer in the ascendant, but hovering in limbo before the inevitable downward trajectory begins. One is to doggedly carry on as if nothing chart-threatening is really happening. The other is to perform the classic Nineties PR stunt of reinvention.
In Geri's case, it may be bimbo's pot luck, but more likely it was the foresight of a smarter sort of ginger biscuit that saw Halliwell quit the Spice Girls while she was well ahead, while Spice World was wooing the box office, album sales were peaking and her star was shining garishly bright.
After the pregnant, post-Spice pause, Geri, now 26, has returned in a radically different guise. She is not looking like Ginger Spice at all - the screech factor has been judiciously bleached out of that angsty two-tone hair, the platform boots and knicker-revealing Union Jack dresses have been given the boot by sensible shoes and longer-length skirts. The pancake makeup of old Spice days has been puritanically sloughed off.
"She's gone from wearing very childish, fashion-conscious gear to wearing stuff that's more grown up and modern," says Liz Baker of image consultants Color Me Beautiful. "Her hair is very sleek, whereas before it was dramatic. She was very heavily made up, very contrived as a Spice Girl, but now looks quite natural - very minimalist and modern." Even her demeanour has changed, from that of bottom-pinching, sassy lassy to the model of discretion, speaking eloquently from the elevated vantage point of various do-goody podiums.
Like all great reinventions, of course, Halliwell's transformation is only part physical. The rest is live action. From the break-up of the Spice Girls in June, until August, all was quiet on the Ginger front. Then Geri sent out a discreet message by auctioning off her stage clothes at Sotheby's and donating the proceeds to a children's cancer charity. "She did the right thing by going quiet, then getting rid of her gear," says Liz Baker. "She was making a PR statement about getting rid of her past life."
The auction was the first of a series of what PR people call PR coups. Since then there has been a double-take front cover for Marie Claire's August issue, featuring a scrub-faced Geri smiling benignly at 416,239 middle-of-the-road female readers.
There has been her very vocal support of the Breakthrough Breast Cancer charity, and the revelation that she, too, had a scare in her late teens, an "absolutely, hideously awful" experience. Halliwell has also written a letter of sympathy to Justine Picardie, whose sister Ruth, a journalist, died at the age of 33 last year with breast cancer. While the former episode is just asking to be pigeon-holed as a calculated PR move, the latter doesn't sit too easily in that spin-doctorish bracket.
But the smartest PR machines know the soft touch can strike just as effectively as a mighty one. The industry trick is to engineer events so that they look like the result of coincidence, as if they are due to serendipity rather than professional strategies. Halliwell's PR agency, Freud Communications, has one of the best reputations in the business, handling that other dodgy firecracker Chris Evans - incidentally, Halliwell's friend and career adviser.
Max Clifford, the infamous image-maker who once claimed that PR is "lies and deceit, massaging the truth, being economical with the truth", thinks that Halliwell's manoeuvres are anything but incidental. "I think they've done a very good job. The look has got to fit in with the image she's trying to create, which at the moment seems to be moving in the direction of Princess Diana."
Take that front cover. Marie Claire are cagey about when it was actually shot, but given glossy production deadlines it may have been as early as March; certainly no later than May. Add some editorial planning into the mix and you're looking at a deal cut long before Geri had left the Spice Girls and her old image behind. That new, fresh-faced look didn't just pop out post-break-up - it was planned at least six months ago and timed to coincide with her sombre public re-emergence.
The Di angle gets more credence with Halliwell's recent appointment as a Goodwill Ambassador to the United Nations Population Fund. But how responsible "they" - Freud Communications - are for Halliwell's new $1m, high-profile position is debatable. Geri appears to have been the passive party in this deal, having been approached by Marie Stopes International to be the British representative of their campaign for safe reproductive health. Events seem to have conspired in a PR-friendly way to cement her new, morally responsible image. "We would never have taken her seriously before," says Liz Baker. "But when she stood behind that podium with her hair pulled back in a chignon, looking like a schoolmarm, she had a new sort of authority."
Somehow, against all the odds stacked up by that trashy, vacuous girl- power veneer, Halliwell has managed to forge a new credibility - and fast. "She's come up with something credible," says Clifford, "and that's very important. But she has to stick with the concept now and be consistent with that image for some time."
Interestingly, Halliwell's reinvention manages to straddle the legacy of the Spice Girls and use it positively in her new Spiceless career - something that Robbie Williams absolutely could not manage after his break from Take That. "I don't think she's alienated her Spice Girls following," says Clifford. "She's managed to keep hold of them and that's a success in itself. The Spice Girls was a launching pad for five girls. Now it's become the launching pad for Geri Halliwell the individual."
Of course, the Spice Girls gave Halliwell her baptism of fire in the art of reinvention. Her early days as a tacky gameshow hostess on Turkish TV and topless/bottomless model - the days prior to 1994 before she spotted that ad for a five-girl band in the Stage - were effectively buried beneath the music industry promo machine until the tabloids industriously dug them up. Relics of those nudie days still abound on the web, though they are outnumbered by the "Goddess Geri" sites that revere her in all her Union-Jacked finery. Her fans, at least, have a Marxist sense of history.
Halliwell's future holds a solo recording career, and possibly film contracts if those recent meetings with Hollywood movie moguls come to more than a couple of Caesar salads on Sunset. Liz Baker is as optimistic as PR pros come. "She's going to come back with something and I think it will be something good."