Kate Middleton's style has been center stage since the beautiful brunette married Prince William last April.

If Middleton is seen wearing a frock from London's Temperley, it sells out within hours. If Middleton is seen wearing white after Labor Day, all fashion rules are forgotten.

She certainly has a clenched hold over the style world; so it is surely no surprise that the Duchess Effect has hit London Fashion Week.

British designers acknowledge the sheer power of Middleton and the Duchess Effect. The lovely lass is breathing new life into royal clothing and looks fantastic, British designer Alice Temperley told the BBC.

She's supporting British fashion by wearing British fashion, which is brilliant, said Temperley. She, along with designers Stella McCartney, Victoria Beckham and McQueen, are all showing fall 2012 collections at this week's event.

The UK brand Whistles saw an astronomical rise in sales after Middleton was photographed wearing a Whistles blouse for her official engagement photos.

We're about to start our international expansion, Jane Shepherdson told the London Telegraph. We've had so much publicity with the Duchess wearing Whistles. We've got to do it now rather than wait too long. We've just opened in Russia and we're expanding to the U.S. and Southeast Asia.

L.K. Bennett's pumps, worn by Middleton, sold out online. Reiss, a family-owned British retailer, saw traffic on its website rise by 200 percent after the Duchess wore one its dresses to meet President Barack Obama and the First Lady Michelle Obama in May, according to ABC News.

Middleton's Alexander McQueen wedding dress was so sought-after that the fashion house made a duplicate version to sell on Net-a-porter, an online luxury fashion retailer.

Middleton's style has gotten her serious fashion cred as well. She was crowned Hat Person of the Year 2011. She and her sister, Pippa Middleton, were also in the running for Vogue's Most Fashionable Sisters award. And rumor had it that Anna Wintour was clamoring to get the blushing bride on the cover of U.S. Vogue.

Now as more Fall 2012 collections show at London Fashion Week, it is clear that Middleton's Duchess Effect has taken on a life of its own. Her regal style seems to have inspired a myriad of designers' lines.

Designer Corrie Nielsen showed a collection complete with Duchess-worthy hats and voluminous queen-esque dresses, while Temperley's line looked as if it were tailored especially for Middleton. Even Pam Hogg's futuristic pieces took a cue from royal style, with regal headpieces, full skirts and high necklines.