NEW YORK - The fashion world, and millions of others, will be holding their breath on April 29 when Britain’s newest and most glamourous royal steps out of a Rolls Royce to tie the knot with Prince William at Westminster Abbey.

While we already know tiny wedding details from the type of cake to the name of the royal harpist, the designer behind Kate Middleton’s wedding dress remains a mystery. The nuptial event the year will be a moment of truth and a ticket to superstardom for one lucky designer.

Rumour has it that the stylish Brit chose a dress by Sarah Burton, a young designer from the house of Alexander McQueen.

“It’s been great publicity for all the British designers who have been featured in the media,” Jill Bradshaw, of the Stylesight fashion forecasting firm, told QMI Agency.

Middleton might not have the same influence on popular culture as the late Princess Diana, but the 29-year-old definitely moves the meter when it comes to selling clothes.

A poll published Tuesday by a British newspaper indicated 70% of respondents thought William’s fiancee was a “fashion icon,” though others say the moniker is premature.

“I find that the media try too quickly to label women in the public eye like Kate and Michelle Obama as fashion icons,” says Toronto image and etiquette consultant Pat Stonehouse. “Kate is definitely stylish and always dresses appropriately. To me Jacqueline Kennedy was a fashion icon.”

Middleton’s style is cosmopolitan as well as conventional. She prefers knee-high boots, flat shoes and plaid skirts. She’s not above mainstream digs from Reiss, Jigsaw and Topshop outlets. Middleton also shows her patriotic side, sporting British brands such as Temperley, Mulberry and Burberry.

Her style endears her to fans around the world. She’s a young woman like them, in the arms of a prince, but continues to shop in public stores.

“I think it’s a good sign, considering the economic situation,” says Stonehouse. “Buying off the rack at Reiss or Issa makes the statement that she can look attractive and stylish without spending a fortune. Michelle Obama did the same. To what degree (Middleton) continues to buy off the rack we will have to wait to see.”

Middleton’s impact on the fashion industry is undeniable and dates back to 2007 when a Topshop dress she wore on her 25th birthday sold out in one day across the UK. Several other items she wore recently have sold like hot cakes in England, proving that girls want to live this fairy tale by proxy.

The grey Burberry trench coat Middleton sported on an official visit a few weeks ago was gone in 24 hours. A $600 navy blue dress by Issa, one of her favourites, also flew off shelves. The Issa brand is reportedly the top seller at London’s Harvey Nichols department store.

The upcoming super-wedding has only intensified the frenzy.

“We saw her engagement dress copied and sold to thousands of younger ladies who look up to her,” said Bradshaw, the New York fashion forecaster “I think the reason she is having this influence on culture is because people identify with her.”

Even Kate’s $390,000 sapphire and diamond engagement ring, formerly worn by Diana, has been copied and is selling like candy. The online shopping site that peddles the $50 duplicates has seen sales jump eight-fold.