Coup for Topshop as Kate Moss set to be its star designer

She has posed for 14 advertising campaigns this season and remains the most talked-about supermodel in the world.

And although she was watching, rather than modelling in, yesterday's Topshop fashion show, what Kate Moss is going to do next still managed to overshadow all else.

Her appearance at the show, held at a theatre in Holland Park, west London, fuelled speculation that the model was planning to design a line of clothes with Topshop guaranteed to have Moss clones queuing around the block.

Although a spokesman for the chain described a possible Kate Moss-for-Topshop collection as "at the moment, speculation", the model's friendly front-row repartee with Philip Green, the boss of Arcadia Group, which owns Topshop, suggested otherwise.

Once the deal is signed, the collaboration will be a marketing coup for Topshop, which has had to watch as rivals H&M scored collaborations with designers Karl Lagerfeld and Stella McCartney.

Although Moss has no experience as a designer - she has been a model since she was spotted at the age of 13 at JFK airport by an agency scout - reaction to the news among the fashion industry insiders at the show was positive. "I think it's very smart of Topshop. She has to be the most stylish woman on the planet," said Terry Jones, editor-in-chief of i-D magazine.

Moss's insouciant style is a proven money-maker. A vest from Topshop which the model once wore, now dubbed the "Kate" vest, is one of the retailer's best-selling items.

Philip Green has already proved he has a passion for the supermodel: in May he paid £60,000 at a charity auction for a minute-long kiss with Moss - although he gave his "prize" away to the socialite Jemima Khan. In the past year the model has topped "best dressed" lists by Glamour and Grazia magazines. "She's been the most influential figure of style of the past 10 years, what she wears, everyone else wants to wear. Her style is cool, ironic, rocky and sexy," said Harriet Quick, fashion features editor at Vogue.

Photographs published by the Mirror last year of Moss allegedly snorting lines of cocaine at a recording studio in west London have done nothing to dent her earning power - quite the contrary. Last September, in the wake of the drugs scandal, Moss may have lost Burberry, H&M and Chanel, but this season she stars in advertising for, among others, Bulgari, Versace, Cavalli, Calvin Klein, Agent Provocateur, Christian Dior and Stella McCartney, and is said to have netted £14m from her season's work.

One only needs to look to America, where celebrities with far less fashion cachet - Donald Trump suits, anyone? - have launched successful fashion collections. In the UK celebrity designers such as Kylie Minogue, Victoria Beckham and Elle Macpherson have put their names to collections of marginal categories such as denim or lingerie.

Until now, Topshop has concentrated on collaborations with young, up-and-coming designers, many of whom will benefit from Arcadia sponsorship this week. Yesterday's show, though, was for its spring/summer Unique collection, a higher-priced line designed by the chain's in-house studio team. Short, A-line summer dresses in steel grey and coral, with dungaree straps and patch pockets, were the most appealing pieces in this show, which is intended to give Topshop the credibility of a designer label.

Since the brand pumps so much cash into London Fashion Week - more than £500,000 on sponsorship schemes - even the most elitist fashion editors find it hard to begrudge the high-street chain its turn on the catwalk.