Princess Bride: Kate's dress will define an era

Her wedding dress will be the symbol of her transformation from commoner to princess, from Kate to Catherine, and define her image to billions of people as they watch her exchange vows with Prince William next spring.

This dress must be elegant, memorable and perfectly fitted. There are delicate balances to be struck: modern but traditional; alluring but not too sexy; classy but not overly opulent, more grown up than Princess Diana's famous meringue confection, with its puffy sleeves and 25-foot train.

Whatever the ultimate choice, expectations are sky high. Middleton has natural good looks and a radiant smile, people seem to wish her well, even if she will be able to afford a dream dress that is far beyond most people's reach.

"I'm not sure if she could pull off a Diana dress, but it would be great if she had something that magnificent," said Mary Alders, 32, a secretary who is looking forward to the royal wedding.

"Whatever it is, everyone will want it. I can see it as silk, maybe some beading. It definitely will be spectacular."

It's all a tall order indeed for a bunch of expensive material cut to fit a young woman's slender frame. But one designer, almost certainly one based in Britain, will soon get the nod for what is expected to be one of the defining dresses of our era.

Vanessa Friedman, style editor of the Financial Times, said the enormous significance of the dress, which will be copied throughout the world, makes it more difficult for Middleton, 28, to choose something simply because it looks great.

"It makes it impossible to pick something just because you like it," Friedman said. "Whatever she picks, it's not about her, it's about what they are going to become. It makes it much more political."

The unstated but very real pressure to pick a British designer, or at the very least a British-based designer, stems in part from national pride and in part from a desire to see a British company benefit from the inevitable "Kate effect" that will bring fame and prospective buyers.

The dress can be expected to shed the best possible light on the designer's entire collection, and is likely to be widely copied in lower-priced versions that will be sold throughout the world, although it is likely the designer will not benefit directly from these imitations.