Since its debut last fall, Gossip Girl has always been more than a television series about its overt subject, the social machinations of Manhattan private-school students.

It has also presented a cavalcade of fashion, its primary viewership of teenagers and young women tuning in not only for the plots, but also to render judgment on the clothes. The extravagant wardrobes of the stars -- a clash of piped blazers, tiny kilts, duelling plaids and festoons of jewellery -- have inspired countless posts on fan websites and magazine features about the female leads.

Now the show's sense of style is having a broader impact, in the retail marketplace. Merchants, designers and trend consultants say that Gossip Girl, which is in summer reruns on the CW network before returning Sept. 1, just in time for back-to-school shopping, is one of the biggest influences on how young women spend.

Fans stride into boutiques bearing magazine tear sheets that feature members of the cast and ask for their exact outfits. Or they order scoop-neck tops and hobo bags by following e-commerce links from the show's website.

"The show has had a profound influence on retail," said Stephanie Solomon, the fashion director for Bloomingdale's, adding that it appeals not just to teenagers but also to women in their 20s, the daughters and the younger sisters of the generation that made Sex and the City requisite viewing for aspiring glamoristas.

Although the series has had only middling success in the ratings, in stylistic terms it "may well be the biggest influence in the youth culture market," said Stephanie Meyerson, a trend spotter for Stylesight, a trend forecasting company.

The show has given an unexpected mass appeal to patrician staples such as crested blazers, layered polo shirts and kilts. When cooler days approach this fall, some retailers are predicting a run on argyle sweaters, knee socks and high boots.

"We tried to launch trends from the get-go," said Eric Daman, the show's costume designer, whose resume includes a stretch working with Patricia Field on costumes for Sex and the City.

"We probably have 50 per cent more of our traffic -- close to 1 million viewers each month -- going into Gossip Girl than into any other show," said Travis Schneider, the founder of StarBrand Media, which handles the e-commerce connections for the series, along with other shows and films including She's the Man and America's Next Top Model.