Who is the real Belle de Jour, the internet's best-read whore?

According to her weblog, Belle de Jour was spending the day indoors yesterday after "waking up to a storm both outside and in my e-mail".

The storm she was referring to was not just yesterday's gales. It was the increasingly frenzied speculation within the publishing world over the identity of the author of an online diary purporting to chart the life of a London prostitute with a penchant for imaginative sex games and quality literature.

This week it appeared that Belle had been unmasked as 33-year-old Sarah Champion, a Manchester-born writer on matters of Nineties alternative culture.

Her name was put forward by Don Foster, an American literary sleuth whose painstaking methods of textual analysis helped to discover the true identity of the author of Primary Colors, a book which gripped the Washington beltway during the Clinton White House years, as Joe Klein.

Mr Foster formed his opinion based on the syntax and local references employed in the weblog. But his suggestion was immediately rejected by Belle's agent at Faber, Patrick Walsh, with whom she has signed a book deal reportedly worth a five-figure sum.

His insistence that the world was no nearer to discovering the truth about Belle was backed up yesterday by Ms Champion's mother, who claimed her daughter was nothing to do with the purveyor of middle-class erotica currently entertaining a rapt audience of both men and women with lurid details of sexual encounters in west London hotels.

But as soon as one name appeared to slip from the frame, another one sprang up to replace it. The new contender is Andrew Orlowski, who grew up on the opposite side of the Pennines to Ms Champion, but with whom she collaborated on a number of minor publications in the early years of the last decade.

Described in some quarters as a "cult figure", Mr Orlowski has a record of cultured sex writing on the internet. Yesterday, however, he was not taking any calls.

Meanwhile, back at Faber, Mr Walsh was telling the world that they were wrong again. "Belle came in this morning. She is not a man. She is who she says she is - a working prostitute," he told the Evening Standard's Londoner's Diary.

And with that denial, yet another name has emerged. This time it is Michel Faber, whose novel The Crimson Petal details the life of a low-rent Victorian call girl with sophisticated tastes.

There are indeed similarities. A typical entry on Belle de Jour's weblog this week reveals an erudite and pornographic inter-coital discourse on the merits of Martin Amis.

But Belle is adamant that she has not been recognised and that the diary is no exercise in middle-class dilettantism.

On Wednesday she wrote: "The people who have been outed as me are not me, and to those for whom it attracted unwanted attention, I apologise. And to those for whom the attention is wanted, are you mad? Still, if you think the mantle of BdJ such an appealing guise, do let us know and I'll have a pair of powder-blue Ginas spirited over to you forthwith."