Dame Vivienne Westwood is back after nearly a decade, but Jonathan Saunders is off and so is the design house Preen.

When it comes to twice-annual London Fashion Week, it's hard to keep up with who is showing their collection in the capital and who has decided to take theirs to New York, Milan or Paris.

This year there's excitement about Westwood returning to the UK from Paris, where she showed in October. Meanwhile, some of the capital's rising stars have gone elsewhere. But what governs this merry-go-round?

Each city is a known centre for some part of the fashion industry, be it the creative capital or the financial one. Designers move from one city to another when they want to build different parts of your business.

Shock

There is a specific route - London, New York, Milan and finally Paris. Each plays a defined role in the creation of a fashion label, says Andrew Groves, head of fashion at Westminster University.

  • 1. London is where designers create a noise and get noticed by the media, usually by designing something weird and wonderful.

  • 2. New York is about showing designs to get financial backing and big accounts with influential stores such a Barneys. By this time the clothes have usually evolved into something more slick and wearable.

  • 3. Milan is somewhere to sort out production, once designers have financial backing. It's generally acknowledged as the city where the best manufacturers are and where the best quality clothes are made, says Mr Groves.

  • 4. Finally, Paris is where they finish once they have a successful design label and business established. Show in the French capital and you have usually made it.
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    Vision

    "Each city plays a distinct role," says Mr Groves. "London is about being creative, New York and Milan are much slicker, more predictable and about business. Paris is more about elegance, as you've usually made it when you show there.


    London is the creative fashion capital

    "London is often 'people's' fashion week because you never know what to expect. The young designers who show there often have nothing but their vision. They don't have the money to put on a lavish show so the only thing they can do to get noticed is shock people. That's exciting because it means anything could happen."

    However, there's some flexibility in this model and Vivienne Westwood's return to the UK catwalk is seen by some in the industry as a bid to return to her creative roots. The publicity generated by such a "return" can't do any harm either.

    While the money and the means of manufacture might not be in London, it is essential as a launch pad. Some of the world's leading designers would never have been successful if it hadn't been for showing collections in the capital.

    "Designers like Alexander McQueen would never have happened without London," says Mr Groves. "None of the other fashion capitals would have allowed such creativity. They just wouldn't show anything so avant-garde and so unwearable."


    Vivienne Westwood, London Fashion Week, 1998
    The doyen of British designers has long deployed shock tactics to make a splash. A riot of colour and clashes are Westwood trademarks, and make good fashion week picture spreads for the UK media.


    Vivienne Westwood, Milan Fashion Week, 2007
    The Italian city is the centre of quality manufacturing, and here Westwood shows off her technical skill with a slouchy yet detailed menswear collection.


    Vivienne Westwood, Paris Fashion Week, 2008
    Beautiful clothes, beautifully cut, by a designer acknowledged as one of Planet Fashion's reigning monarchs. Showing in Paris only confirms her status as a grande dame.


    Matthew Williamson, London Fashion Week, 1999
    Some designers go for punky street cred to grab attention in London; Williamson went the risque route with the help of the hottest models of the moment - here barely cloaking Naomi Campbell in pink and gold.


    Matthew Williamson, New York Fashion Week, 2004
    Having made his name in London, Williamson defected to New York in 2002. Gone were the dresses no bigger than a handkerchief in favour of clothes real women with real money might wear.


    Matthew Williamson, Milan Fashion Week, 2008
    From one of the 1990s hot young designers to chief designer at Pucci, Williamson has joined the fashion elite and revived the fortunes of the Italian brand. Where better to show than Milan?