The wanness of a grey March day fades into memory approximately one footstep inside Matthew Williamson’s Mayfair townhouse headquarters. Downstairs, pinks and purples jostle for attention in place of the typical office greige. Upstairs, his pre-fall collection hangs in rails along the walls of an elegantly proportioned room. The wintry weather outdoors is no competition for the vitality of the prints and textures within.

Williamson glides into the room in a battered black biker jacket of the sort that friend Sienna Miller might throw on over one of the designer’s long, wafty dresses. Close on his heels is Coco, a black cocker spaniel who spends the next hour snoozing contentedly at the designer’s feet.

It’s been 15 years since Williamson launched his brand, a step he took three years after graduating from Central Saint Martins. At his debut show, Kate Moss and Helena Christensen slinked down the runway in body-skimming bird-of-paradise dresses. Williamson called the show—all four minutes and 11 looks of it—the Electric Angels collection, and it came as a vivid riposte to an otherwise ‘very dark, austere, androgynous period,’ in London fashion.

It’s still one of his three favourite shows. ‘It was done with such naive innocence,’ he says. ‘The audience had no seats.’ Back then, Williamson (with partner Joseph Velosa) had little sense of what to expect from running an independent fashion label, but he did have the conviction that he was on the right path.

‘I had an idea and concept and wanted to say something with the clothes I was doing,’ he says. ‘We have a very strong DNA centred around this idea of travel and jet-set sensibilities and bohemian spirit.... It’s a rich pool that we’ve had since day one.’

Stockists, magazine covers, a standalone store (‘the moment I felt like we were becoming a brand as opposed to a label,’ he says) and an H&M designer collaboration followed. Along the way, a ‘Matthew Williamson dress’ became shorthand for a richly embellished chiffon slip of a thing, pitch-perfect for dancing under the Ibizan moon—or making the wearer feel as though she could. Miller (and now Dree Hemingway) embodied the brand and dangled the promise of similarly vibrant lifestyles to would-be Williamson-ites.

Today, ‘it’s got the same essence, but it’s a little more fine-tuned,’ Williamson says. His autumn winter 2012 collection, based on ‘the idea of a girl who resided in a stately home and was inspired by the interiors and surroundings,’ conveyed a more sharply futuristic and forward-looking air than recent seasons.

‘Certainly in the last two to three years the collection has become more polished, a little more refined, a little more grown-up,’ he says. ‘As I age I want to design slightly differently to how I designed in my 20s.’

He does business differently at 40 than he did at 25 too. Williamson now employs 47 people. He produces four mainline collections a year, plus the MW by Matthew Williamson diffusion line, a bridal collection and the Butterfly by Matthew Williamson at Debenhams range. Recently he partnered with Sony on the electronics giant’s latest range of Cyber-shot cameras, which he says he used to keep track of models and looks in the run-up to . He’s getting into Facebook.

There’s also the matter of the 15th anniversary and how to mark it. Plans are underway for a party and possibly a short film—opportunities for Williamsonian party dresses if ever we knew them.

The demands of so many commitments lead to a ‘relentless’ working pace and ‘right—what’s next?’ mentality, Williamson says. First up, he needs to start designing pre-spring. As soon as Williamson showed the AW12 collection, his head designer began their research. ‘We need to—we’re late,’ he says.

‘It’s a job that isn’t a job; it seeps into your everyday life,’ he says. ‘It gets more and more intense, but I have wanted to do this since I was a child and I’m lucky that I’m still doing what I love now.’

ELLE met Matthew Williamson to discuss his collaboration with Sony and the new range of Cyber-shot cameras.