Scroll down to watch a backstage video shot at the Matthew Williamson show

There’s a feeling, palpable among some of London’s younger designers, that they can crack the market without celebrities. Christopher Kane, part of the new vanguard of talent, was quoted yesterday in The Times on why he wouldn’t be “gifting” any of his dresses to Victoria Beckham. Subtext: this woman is irredeemably uncool.

But hook the right celebrity and London’s fashion crowd proves to be as starstruck as everyone else.

So when the diminutive figure in the big hat and Jimmy Choos sitting in the front row at Matthew Williamson’s show began moaning suggestively into the microphone and, before most people had noticed what was happening, jumped up to join his dancers on the catwalk, the audience came as close to erupting as fashion audiences allow themselves. Had it not been for their precarious heels, insistent hangovers from fashion week’s multiple parties and that expressions of emotion are generally deemed unchic, they might even have stood up.

Williamson’s relations with celebrities have always been blessed. Publicity-wise they have helped him to punch above his weight and undoubtedly gave him his foothold in the US. Kate Moss, Helena Christensen and Jade Jagger modelled in his first show. Ten years on, celebrity inflation meant that he needed to pull something bigger out of the bag. Even at 5ft and pushing 50, Prince is a major draw.

This was an extra fillip to what is turning out to be an almost spookily successful few days. Luckily once people had finished texting Prince photos to everyone they knew, the parade of clothes in front of them showed that Williamson was on top form. Before the show he admitted to first-night nerves, exacerbated by this being his ten-year anniversary show and his first in London in half a decade. Being part of New York Fashion Week has clearly taught him how to parlay his brand of Ibizan hippy playfulness into some luxurious, desirable pieces with just enough originality to make an entrance without looking as though he’d bothered. Naturally he’d worked like a Trojan to achieve the effortless look. From the African prints (a strong trend for spring) on his slim tunic top, the neon bright lace-up sandal-boots and rosette-strewn chiffon dresses to the Masai beading on his rough linen dresses and tie-dye trimmed muslin dresses, this was the confident, polished collection of a designer who knows exactly what works for him and his expanding clientele of rich party-on-the-private-beach-goers.

Pity the poor designer who had to compete with that. Still, Betty Jackson hasn’t survived more than a quarter of a century for nothing. The woman who famously dressed Jennifer Saunders and Joanna Lumley in Ab Fab is, as she demonstrated yesterday, as adept at harnessing a passing trend as David Cameron. Featherweight, toffee-coloured leathers sliced into streamlined coats and jackets? Bingo. Printed strapless dresses with dirndl skirts worn over knitted vests? Spot on. Next season’s primary-coloured, patent platform sandals, exposed zips? Ditto. But it takes more than trends to survive as a designer, given how well Primark and Co have got that trick covered. Jackson’s strength is her ability to stamp her own mark on the look du jour. The pretty pleating on the back of a coat collar, the subtle sprinkling of sparkles on a loose midnight blue shift struck the right balance between whimsical, almost 1950s couture details and that industrialised-hippy look that Marni has made so popular. Could have done with Prince though.

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