The designer John Rocha is a famously nice individual in a world in which niceness is not a superabundant quality. Mention his name and even the flintiest fashionista will emit little trilling and cooing sounds. Put this in the context of having spent more than 20 years in the industry and positively Croesian commercial success (his worldwide turnover in 2006 was £135.5 million), and this niceness begins to take on an almost metaphysical quality. Indeed, despite his diffidence concerning his idiosyncratic looks (he is invariably compared to a Native American chieftain, but he himself favours the analogy of a basset hound), in the flesh, his serenity has a beatific quality that renders him curiously beautiful. Once in his presence, you don’t quite want to leave it, a phenomenon reflected in the loyalty of the team he has amassed around him, the majority of whom are Rocha lifers.

Rocha’s is the ultimate rags-to-riches story. Now 54, he was born in Hong Kong of impoverished Portugese/Chinese parentage. (His English remains endearingly rough around the edges; his proudest moment was being awarded a CBE in 2002.) “I come from a very working-class background,” he beams with not one iota of chippiness. “Seven brothers and sisters living in 400sq ft, with no air conditioning.

I arrived in London at 17 with £13 in my pocket. To end up where I am, with a wonderful family, houses in Dublin, France and London, fishing four weeks of the year… I really appreciate what I have.”

He has achieved this turnaround in fortune by consistently forging his own path: refusing to follow the power-dressing herd in the Eighties and abandon his love of craftsmanship; making Dublin his base over London; and spearheading the trend towards diversification and “masstige” that has been adopted industry-wide. The Rocha reach not only incorporates his successful collaboration with Debenhams, but forays into crystal, interior design, jewellery and architecture. He’s a Renaissance man – polymath first, business brain second – employing a financial controller so he “never has to think about it” and focusing instead on which Picasso or Matisse to choose to supplement his imposing art collection.

We meet in a café around the corner from the new London store he is opening in Dover Street. The decision to opt for W1 will inevitably be seen as part of the “new Mayfair” vogue that has witnessed fashion folk flock to the area: Stella McCartney, Matthew Williamson, Marc Jacobs, and soon-to-be arriving Diane von Furstenberg and Balenciaga. In fact, Rocha has long been part of the neighbourhood, living at Claridge’s when in the capital.

The new emporium is as exquisitely ornamented as one would expect: crystal-bedecked walls, sumptuous velvet drapes and rustic 1930s tiling. The 350-year-old building is a former pub, full of nooks and crannies to accommodate the many pies in which Rocha has fingers. There will be a crystal room to reflect his work with Waterford; men’s, women’s and children’s wear sections; jewellery; beauty products; books; a conservatory; and upper floors constituting his London home. “It was time to put everything together in a building I could put my signature to,” he explains.

Asked to summarise the vision that unites his many activities, he answers: “I like to create things that don’t just look great now, but will also look great in ten years’ time. I always work with craftspeople who have a traditional skill, but involve them in a modern form so that it works with what we do now, but will have the integrity of a beautiful thing from the past, too.”

It’s a Rocha hallmark that, while being in no sense fashion resistant, he is stalwartly fashion-victim resistant. Still, the industry remains his consummate love, the wellspring of his placid yet relentless energy. “It’s the foundation of what I do. You challenge yourself every six months, putting on a show for 600 people – the best buyers, the best journalists – and you think: ‘I’d better not make a boo-boo of this.’”

Keeping him boo-boo free is his wife, Odette, who acts as design partner for the women’s collection. “I think the way men think, but she’ll say: ‘Don’t make the trousers like that – I can’t sit down.’ We’ve been a team for 25 years.”

Rocha is not a designer who prefers his creations on paper rather than on the body, taking a robust attitude to the issue of body shape. “I design for a purpose. We start at size 8 and finish at 14, and our in-house model is a healthy size 10. I dress everyone from students to superstars. The end user is what I am, what I do.”

If a week is a long time in politics, then 20 years is several aeons in fashion, where careers come and go in a mascara-ed eye blink. What is the secret of his longevity? “What I do is like building a house – every season I add a bit more.” And now this house will find a home in Dover Street. Having kicked off the craze for haute design on the high street, Rocha is poised to be a dominant force in fashion’s much-vaunted return to quality and artisanship. He believes that accessible fashion and its more esoteric manifestations will happily co-exist, as they do within his own oeuvre. “But that’s only my opinion.” It is an opinion worth rather more than most.

15a Dover St, London W1 (020-7495 2233; www.johnrocha.ie)

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