LONDON - It might have been a casual shopping trip, or it might have been ... something more.

Britain's royal watchers are on pins and needles over even the smallest details about Prince William's upcoming wedding to Kate Middleton. In the frenzied pre-wedding atmosphere, a visit by the bride's mother and sister to Bruce Oldfield, one of Britain's leading fashion designers, is seen as an indication that Middleton may be using him to design The Dress for her April 29 union.

"He's just shot to the top of the list," said Peta Hunt, fashion director for You and Your Wedding magazine. She said the fact that Carole and Pippa Middleton, who are both known to take a low-key approach to fashion, spent 90 minutes with Oldfield at his salon is a sign that he is doing some designing related to the wedding.

Of course, it's always possible Oldfield may be making gowns for the mother and sister of the bride, but not the bride herself, or that Carole and Pippa Middleton stopped in to buy accessories for another event.

Still, Hunt said Oldfield would do a superb job if he is, indeed, the chosen one.

"He has a simple elegant touch which would be ideal for Kate," she said.

The identity of the actual dressmaker is a closely guarded secret. Oldfield's spokeswoman Monday refused to comment, and palace officials said the dress choice is a "private matter" because Kate Middleton wants to be able to surprise her fiance on their wedding day.

There have been earlier boomlets of speculation about Oldfield, who was one of Princess Diana's favorite designers.

He concocted many dresses for Diana over the years and has also developed a celebrity following that includes Catherine Zeta Jones, Sienna Miller and Barbra Streisand.

Oldfield, 60, was mentioned as a possible choice to design Middleton's dress when the royal engagement was announced in November. In December, designer Ben di Lisi created a stir when he said he had heard that Oldfield had been chosen.

London bookmakers have slashed their odds on Oldfield designing the gown since news of the Middletons' visit to his salon came out because so many people expect him to get the choice assignment -- if he doesn't already have it.