My first thought, on hearing that Kate Moss will be sitting behind the big X Factor desk, is: how does a fashion model have the expertise to judge a singing competition? It isn’t her ability to hold a note that got Moss the offer, of course. She is going to be the latest face of music TV because the British fashion and entertainment industries have struck up a romance.

This isn’t the only developing love affair in the worlds of fashion and entertainment, which are now seemingly awash with Power Couples. It’s a cross-pollination that Vogue’s fashion features director, Harriet Quick, believes was inevitable. “Several figures are seeing how the interface of fashion can work brilliantly in the arena of entertainment. Two names,” she rightly points out, “are bigger than one”.

Moss and Cowell might be sitting next to each other on TV, but Simon Fuller is the one spending the money. The announcement last week that 19 Management, the company he set up to handle musical artists including the Spice Girls and Amy Winehouse, had bought a 51 per cent ownership stake in Storm Model Management means that Fuller and Storm reign supreme when it comes to fashion and media couplings. With his new controlling share, Fuller has access to names including Carla Bruni, Lily Cole, Cindy Crawford, Emma Watson, Jourdan Dunn and of course Kate Moss.

In his words, he wants to “push the boundaries, blur the lines and redefine what a model agency should be in this fast-moving world where fashion is playing an increasingly important role in setting and reflecting culture and tastes.” If nothing else, it’s a great estimation of where the fashion industry is heading.

Fuller, in fact, could singlehandedly fill up the top four spots in the Power List. He entered the fashion arena in August 2006 through a joint venture with the designer Roland Mouret, called 19RM. Mouret, who after an ugly split from his previous backers had lost the rights to his own name, did well to find Fuller. Just think about all the beautiful celebrities — always happy to accept and wear a new dress — on his books. It is the access and crossover between fashion item, celebrity wearer and public obsession with paparazzi shots, that makes the deals so worthwhile to all parties.

Fuller has also launched the Beckhams’ fashion label, dVb, which includes fragrance, denim, sunglasses and Victoria Beckham’s own well-received line. The rumoured retail value of this partnership is in excess of $200 million. Next up for the former record company executive is the soon-to-be-launched fashion media title Fashionair.com.

Kate Moss and Sir Philip Green are another lucrative coupling. After Moss signed a deal, in autumn 2006, to design an eponymous range for Topshop, their relationship set a new standard in retail marketing. Its success (the autumn/winter 2009 collection will be her eleventh) proves how lucrative the union of two big fashion personalities can be.

With a new business venture in the pipeline between Green and Cowell, the links look set to become even more closely woven. It makes you wonder whether, one day, these new fashion and entertainment conglomerates could rival the so-far-untouched French umbrella firms of LVMH and Pinault-Printemps-Redoute, which control brands including Gucci, Alexander McQueen and Stella McCartney. They certainly have the fashion names, but now seem lacking in media crossover.

The fashion media model came from the United States, or rather, via the Miramax film mogul Harvey Weinstein. Fuller has access to some well-papped celebrities, but Weinstein’s leading ladies pretty much cover the board. This probably explains why at least one of them - Scarlett Johansson, say, or Renee Zellweger - will often wear a Marchesa gown at a big red-carpet event. Marchesa, of course, is the eveningwear label set up by Weinstein’s now wife Georgina Chapman and her business partner, Keren Craig.(Both the couple and the label launched in 2004.) Weinstein, on the back of this success, seems to have realised that the future is in collaboration: his latest is with Tamara Mellon, the creative director of his label Halston.

The Fashion Power List may be relatively compact at the moment, but it is still a potent demonstration of how the fashion industry is changing. The importance of television, cinema and celebrity might not please the design purists, but it sure as hell brings in the money.

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