Every girl's best friend: Designer Alber Elbaz

We put a lot of work into the windows," says the designer Alber Elbaz, standing in Mount Street on a rainy Wednesday afternoon and surveying the fruits of any labours on the eve of the opening of London's first Lanvin store. "There had to be a story. It's a family portrait. Like the Royal Family. Our kind of Royal Family."

Certainly, the mannequins in question, resplendent in beauty pageant sashes and with French pink, brightest blue and sunshine yellow hair, bear little resemblance to the stolid grandeur of the Windsors. Equally their pop art coloured leopard print silk cocktail dresses, draped and tucked with a lightness that is unparalleled, are never likely to be seen on the back of Her Majesty The Queen or indeed her horsey progeny. Instead here are bouncing baby mannequins and proudly plastic "mothers, daughters, daughters-in-law", all set against a huge gilt-framed mirror upon which has been scrawled in red lipstick "I love Lanvin, Lanvin loves you".

Inside Elbaz declares: "I like the idea of a supermarket." Suffice it to say that, in this case once again, Asda isn't the first thing that springs to mind. It is true though that the many Lanvin capsule collections – the hugely successful and more reasonably priced collaboration with Swedish denim company, Acne, "collection blanche" aimed at the type of bride who would rather wear a beaded and embroidered T-shirt reading "just married" or a tiered sweet nothing made out of nothing more haute than frayed jersey than the traditional meringue – are all given their own vitrines. There's 22 Faubourg St Honoré, featuring reworked classics from ballerina shoes to bias cut dresses, the prohibitively expensive but always beautiful main line, candy coloured bags, crystal encrusted silk shoes, costume jewellery – Lanvin is almost single-handedly responsible for the revival of this craftform. It's all piled up apparently spontaneously – the display in question, it almost goes without saying, is as considered as everything else Elbaz touches – and with a warmth and humanity that is a million miles away from what might be expected from such a grand, quintessentially Parisian status label.

Neither is Israeli-born Elbaz in person the typical fashion designer. Much has been made of his roundness, not least by himself. "Do you think I go to the beach in a swimsuit? Never! But then I'm Jewish. I'm a worrier. I worry about everything. I cannot not worry. If you ever see me some time and I'm not worried... worry."

His dress code, equally, is as proudly individual and unexpected as his work, comprising today, as always, heavy-rimmed black glasses, a tuxedo, the trousers of which are very slightly too short, a white shirt and a bow tie, fastened loosely and deliberately askew.

In a world that thrives on dictatorial tendencies – despite a loosening of acceptable dress codes, there is still always a certain skirt length, a certain volume, a certain colour that fashion decrees de rigueur – Elbaz is more interested in the idea that his clothes should be determined by those who actually wear them.

"You know, in the Nineties designers insisted their clothes should be worn a certain way or styled in a certain direction but I don't think that works any more", the designer argues. "Fashion designers – and design in general – should no longer be about dictating. It's unrealistic and irrelevant to every day life.

"The first thing anyone asks me at the moment," he continues, "is how and why are you opening a store in London when the economy is so bad? And you know what, it's not because we got a good deal, that's not it. I think we're coming to London because in times like these, besides chocolate or perhaps a rose, maybe the only thing that will make you feel good is a pink dress. Of course, we've all lost money, we're not on the street though, and in order to feel better, to go forward you have to look good, you have to feel good."

Since he arrived in 2002, Elbaz has transformed Lanvin – France's oldest couture house, founded by Britanny-born Jeanne Lanvin in 1889 and bought in 2001 by Mesdames Wong, Yong and Merieux – from relative obscurity into one of the jewels in international fashion's crown. It remains a small company but a highly successful one nonetheless. Kate Moss wears Lanvin and so too does Linda Evangelista and just about every fashion editor worth her credentials. Everyone from Tilda Swinton to Natalie Portman rely on it for the most contemporary take on red carpet dressing in the world. Visit a Lanvin store, though, and don't be surprised to see more than just the hard-bitten insider cooing over the softness of the fabric, the intensity of the colour, the easy and supremely flattering nature of the silhouette all of which apparently prove impossible to resist.

"At the end of the day, it's going back to desire," the designer confirms. "There is no formula that I have. I don't sell formula. In fact, I'm afraid of it. I think that we do put an awful lot of emotion and thought into our work."

Elbaz' family is of Moroccan origin. He was born in Casablanca in 1961 and brought up in Tel Aviv where he also studied fashion. Following graduation from the Shenkar College, the Tel Aviv School of Fashion and Textiles, he moved to New York. "I worked for a company that was doing mother of the bride dresses for $150 or something – and that was expensive," he laughs. After two years, however, he was introduced to Dawn Mello, the woman best known for installing Tom Ford at Gucci – but more of him later – who suggested that this talented young designer might like to work with Geoffrey Beene. Elbaz was Beene's righthand man for no less than seven years. "It was an amazing place to work," he told me when we first met, "the best school. I stayed there because I was happy working a little bit outside the circuit, because he had his vision about fashion, because he had the best style, because he was all about design and because he was a wonderful man."

By the mid-Nineties, however, it was time to move on. Elbaz relocated to Paris having been head-hunted by Guy Laroche and then Yves Saint Laurent – Elbaz was chosen personally by the most famous figure in French fashion to design the Yves Saint Laurent Rive Gauche women's ready-to-wear collection when he stepped down in 1998. Elbaz's tenure there lasted only two seasons. In 1999, the Gucci Group bought the label and aforementioned Ford was unable to resist the challenge of taking over as creative director himself.

Elbaz has made no secret of the crisis of confidence that followed his split from Yves Saint Laurent, which was announced in just the well-mannered fashion that might be expected, given the milieu in question, but which he has since described as "my dark room". For a year the designer travelled the world and then, having returned and turned down various appointments, he accepted the position at Lanvin. "It was all very direct. It was meant to happen. I was so happy because I thought I would never be able to find myself."

Today, Elbaz is one of the most respected figures in contemporary fashion. His perfectly constructed and quietly lovely clothing is the envy of women both within the fashion industry and without. Be it a cocktail dress or a trench coat – and both are by now time-honoured signatures – there is a sensitivity to the finished garment, constructed with a consideration and attention to detail worthy of haute couture that makes it not only gorgeous but also a pleasure to wear. And Elbaz is perhaps right in thinking that such simple pleasures are much needed right now.

They come at a price, of course, but, as the designer is quick to point out: "I think it's totally important today to understand the current situation but not to be a chicken and say, let's do just cheap trousers and cheap T-shirts. Neither is it right to go totally dark, totally down. Of course we have to make sure that the prices of at least some items are not too crazy but it's also about the fact that if we go too low we will kill all the know-how, the tradition and then we will never be able to find it again.

"Everything is very tough," Alber Elbaz concludes, "but perhaps that will make us stronger. You remember what was going on just a year ago, there was so much product, the bigger the better, and it was all moving so fast that there was almost no value to anything. Now that everything is more cut back and lean maybe we understand the importance of certain things, maybe we can appreciate them more."

Lanvin, 128 Mount Street, London W1