Yes, Geri - it's hard to break out when you're cast in plastic

WHAT most amazed me about Geri "Ginger" Spice's departure from the Fab Fivesome was that she said two years of superstardom had left her "disillusioned and exhausted".

Exhausted I can countenance: think of the Pan European tour, the numerous videos, the endorsement of everything from Chupa-Chups to Impulse Bodyspray. Simply the amount of different costumes demanded by Spiceworld The Movie were enough to give everyone nervous exhaustion.

But disillusioned? For a band that invented the glorious manifesto of Girlpower?

Indeed, "girls" is the wrong label for the Spices; they aren't girls any more than Tony Blair's new female colleagues are babes. These icons of pre-teen pop culture are switched-on business women.

Geri in particular has made an estimated pounds 13m out of the venture; apparently she didn't go for the major shopping experiences favoured by the other four (who each made pounds 10m), but saved her money for the day the bubble burst (yesterday at 2pm).

There is no question the Spices have done well out of their stardom, and no one should begrudge them for it.

They knocked out some groovy tunes and proved to be ironic as well as populist. They made a pop bio-flick which could be enjoyed by the over- 12s. They even dumped their manager at the height of their powers and made a go of it alone.

So why then was Ginger disillusioned? She never had a sex `n' tell scandal; she never publicly resorted to drink, drugs or drying out; her legs were never outed as cellulite-covered.

She always managed to look the part, even when cringy footage of her former life as a Turkish gameshow hostess was plastered all over the tabloids and television quizzes.

Perhaps Ginger's disillusionment came from the realisation that sometimes it is more fun to travel than to arrive.

The most exciting part of being a Spice Girl may not have been launching your own film in Cannes, or meeting everyone from Nelson Mandela to Prince Charles. It was pulling it off in the first place.

Of course, it was all fictional. Everyone knew the Spice Girls were as natural a creation as The Monkees, but for some odd reason the Mels, Baby, Posh and Ginger clicked as much as any "proper" band did.

And so Ginger might simply be yearning for the days when Turkish light- entertainment was still a recent memory, or that moment when, raw and unsigned, the Fivesome sang "Wannabe" before the head of A&E at Virgin.

Perhaps the fear of being disillusioned is why rich and famous people simply can't stay still. Richard Branson delves into the world of high- flying balloons; John Travolta transmogrifies himself into Bill Clinton for a film; even George Michael probably had method behind his recent madness.

However, the Spice Girls had to stay still. As with their distant cousin Barbie, they were cast in plastic.

I put it down to their nicknames. Never originally part of the plan, they became the most brilliant marketing tool of all.

When you're a Spice, you stand by your moniker. Which means that Sporty can't ever really turn up in a ball-gown; Baby can't take a Masters degree; Posh can't slum around in a track-suit. And so it was for Geri; her glamourpuss creation simply wasn't flexible enough for her to move on.

There is, of course, another theory, highly laddish and rather patronising. According to some commentators, Geri left the Spice Girls because Mel B bullied her, laughed at her dancing and said she couldn't sing.

Girlie teasing? For a Turkish gameshow hostess who rose to make millions and became one of the familiar faces of the decade? Don't make me choke on my Chupa-Chup.

Rosie Millard is the BBC's arts correspondent.