Isabel Marant for H&M: Collection designer is no Karl Lagerfeld

Marant is a household name in France but she's a step down next to the other talents H&M have tapped, says Alexander Fury

French dressing: Isabel Marant's designs for H&M

You may already be in a scrum outside an H&M store reading this. You may be steeling yourself for the trip. Or you may have no idea what the hubbub you passed on your way to work is all about. The fuss is over French designer Isabel Marant's "masstige" collaboration with high street behemoth H&M. And, as that clumsy portmanteau betrays, it's yet another chance to get your hands on a piece of designer clobber at a bargain-basement price.

Mademoiselle Marant is no Karl Lagerfeld, the designer who fronted H&M's first high-end collaboration in 2004. His name, and his sunglassed, ponytailed countenance, were immediately recognisable, as was his fashion sense.

In some eyes – mine at, least – Marant is a step down next to the other talents H&M have tapped. Rei Kawakubo's Comme des Garçons and Maison Martin Margiela changed the course of contemporary fashion, questioning postmodern notions of luxury.

Isabel Marant makes jeans, embroidered jackets and fringed suede booties. Her most noteworthy contribution to the state of modern dress is that hybrid of training-shoe and trotter, the "wedge sneaker". It's an unholy coupling, but for the past few years it has proved ubiquitous, a fashion verruca we're not yet shut of.

I'm being harsh. But honest. Isabel Marant herself would probably agree: "I wanted to create clothes that I myself wished to buy," she stated, simply, to L'Express a decade ago.

Marant was born in Paris in 1967. Her mother was a director of the Elite model agency (and a model herself). She began customising her own clothes as a teenager.

Parisian fashion designer Isabel Marant (Getty Images)

In the mid-Eighties she designed a few pieces with Christophe Lemaire (now head designer of Hermès, a bastion of French hyper-luxury), the success of which encouraged her to abort plans to study economics: she enrolled at the Studio Berçot fashion school instead.

After working alongside designers such as Chloé, Claude Montana and Martine Sitbon, Marant established her own label in 1994 and began showing her collections as part of Paris Fashion Week. Success was swift.

Marant's success is also due, in no small part, to Emmanuelle Alt, Paris Vogue's editor in chief and for many years the stylist for Marant's label. Hence the fact that Isabel Marant became the "uniform" of the Paris Vogue set: impossibly skinny jeans, oversized jackets, unwashed hair, spindly heels.

Off-duty models also love its nonchalance – fashionese for "slept in", a snippy phrase thrown about a lot when describing her aesthetic. In the past, it's been slept-in rock-chick, or slept-in with Navajo embroidery. Autumn/winter 2013 was slept-in with studs.

Isabel Marant's look has ousted the stripey T-shirt and beret as the national costume of France. At least, for French fashion-followers. She's doing a roaring trade: cannily, her prices fall shy of high-fashion high-fliers. Marant's knitwear can be yours for around £300, a coat for £800.

Hefty, but hardly stratospheric. Otherwise, she punches like a heavyweight. Isabel Marant, and its signature cross-hatched asterix star logo advertises in all the glossies, and is stocked in 35 countries. She has 14 standalone stores, including one on chi-chi Bruton Street in London's Mayfair.

Isabel Marant may not be the world's greatest fashion designer, but she has the connections to know what's going to be cool before the rest of us. And that's what's got the crowds queuing at H&M this morning.