Phillipa Lepley is the sudden new addition, after a bookmaker slashed odds on her being the chosen one. The betting firm of William Hill said it had had received several three-figure bets on Thursday.
Lepley is known for her elegant designs and has made dresses for some well-known British celebrities. A spokeswoman at the couture store in Chelsea, West London, refused to comment.
Rupert Adams, a spokesman for William Hill, confirms that they had more than 1,000 pounds – about $1,600 – suddenly wagered on the designer.
"There is rarely smoke without fire, and I would suggest she is possibly in the running and on a shortlist," he tells PEOPLE.
Adams also suggests that the palace might soon announce a wedding date – possibly as soon as Friday, say news reports on both sides of the Atlantic. The company suspended betting on April being the magic month after "so many people" started trying to guess that a spring date would be the one.
Friends are saying that William wants to wed early as possible, while palace insiders have suggested summer may be more suitable.