There was a moment when the new intake of girls at school stopped being brace-muzzled, awkward creatures in baggy flares and neon tops, with their eyes ringed in zingy, badly applied electric blue mascara. It coincided with the moment when Topshop became a fashionable, on-trend outlet; taking looks straight off the catwalk and onto the average person in the street, placing everyone suddenly within reach of style.

The girls became leggy, blonde and polished, arriving with their thirteen-year-old fashion senses already honed and with wardrobes to match. Topshop stopped being a place where you could buy a vest, jumper or T-shirt in every colour of the rainbow, and became a chain of fashion palaces, complete with ‘shoe lounges’, nail bars and shiny new shop fronts.

Did ex-director Jane Shepherdson’s phenomenal rebranding exercise (which undoubtedly changed the face of the British high street) rebrand the consumers themselves, or was it just a case of the right strategy at the right time?

One thing is certain, British teenagers are now rated the most fashion-obsessed in the world:

‘The advertising agency JWT recently asked young people in the UK, America, Brazil, Canada and Australia which items they would never cut back on, no matter how tight their finances. Brits ranked “buying new clothes” higher than any other nation in the poll.’

This isn’t in traditionally chic France or in sun-kissed Hollywood. This is in Britain, never internationally renowned for the beauty of its people or their style sense. But that’s all changed.

It is no coincidence that in the past decade, the rise of a youth culture fixated by fashion and celebrity has been so marked in Britain. Teen idol Emma Watson’s decision to head Stateside for university to be ‘more anonymous’ says a lot about the kind of world Brits are growing up in.

This trend of fashion-obsessed teenagers doesn’t mean they’re all running around in designer labels, flashing Louboutin soles. The astronomical growth of sites like ASOS.com (As Seen on Screen) demonstrates the fact that everyone now wants access to celebrity wardrobes, high fashion, runway styles and the associated glamour, all in a purse-friendly, disposable form. Yes, the odd birthday presents might be iPhones and Marc Jacobs bags, but the average purchases of these teenagers are under £40 and happening every week.

Going back to the discussion last month about Madonna and Jimmy Choo taking to the High Street, perhaps this is the most financially savvy move brands can make. By jumping onto the Topshop/ASOS bandwagon of affordable yet aspirational trends that teens can buy into week in, week out, big brands can sell to the most important emergent demographic; one that has a large disposable income, but is also surprisingly discerning.

Sarah Ventress – @sarahventress