Naturally the designer herself embodies the style best. It's 2pm on a Sunday afternoon when we meet in her showroom in Paris. Marant doesn't look fresh as a daisy. Instead she looks like she has just got out of bed, with her freshly scrubbed skin and messy ponytail. Her unkempt appearance, however, only complements her worn-in red tweed jacket with rounded shoulders, skinny trousers and thigh-high suede boots.

'It's cosy, chic and elegant but also very Parisian. French girls look like they don't care about how they look but they really do, a lot,' says Marant. 'My look is quite simple, but with the right flair and presentation. It's all about an attitude.'

It's hard to imagine this down-to-earth designer ever having attitude. The daughter of a German model and Frenchman, Marant was raised in a modest Paris home and became interested in fashion as a young child. During her teens she would design and make clothes for her friends on a sewing machine bought by her father. This passion led her to give up a career in economics, opting instead to study ready-to-wear at the famed Studio Bercot in Paris.

Upon graduating she launched a jewellery line, creating statement pieces under her own label while freelancing for designers such as Claude Montana.

By the 1980s she had raised enough capital to launch a knitwear line, together with her mother. When her mother left the business a few years later, she went solo and launched her eponymous label, Isabel Marant, in 1994.

The brand quickly won its place among the stylish Parisian set, thanks to its ethnic overtones and boho charm. As the collections grew, Marant perfected items that would eventually become her signatures, from the boyish jackets, embroidered blouses and skinny scarves to slouchy trousers, little dresses and embellished boots. Best of all, these pieces could be worn time and time again, regardless of trends.

'My style has always been very consistent. I am not a creative designer like Galliano - my aim is to dress up girls every day. It's a different thing altogether and it's what I am good at,' she says.

'A journalist once said something that is very true - Isabel Marant clothes are like old friends you always have in your drawer. I hate something that looks too new and that you are afraid to wear because you don't want to ruin it. It's important that when you buy clothes it feels comfortable and pretty.

'It's always been difficult for me to design clothes that will be chucked away. For me a garment that is wearable is one that you keep in a drawer for years.'

While Marant built a strong following in France for the next 15 years, it came to a point where she got stuck in a rut. While her designs maintained their wearability, she still lacked a defined style. She also needed to translate this French look into one that would appeal rather than intimidate an international audience.

'I'd always wanted to do more, to take it the next level but I was afraid. Then when I started working with Emmanuelle it all came together. She has a very good view of what I am and what my clothes are about,' she says.

The Emmanuelle she is referring to is of course Emmanuelle Alt, fashion director of French Vogue and incubator of all things stylish. Old childhood friends, the two had lost touch until Alt's husband Franck Durand joined Marant as creative director a few years ago. Their reunion sparked off something that would change the brand completely.

'I'd always told Franck how much I loved Emmanuelle's work and how I would love to work with her. My strength is not putting clothes together, I know how to dress myself but I am not good at taking my clothes and styling it together. Emmanuelle on the other hand is perfect for this. She comes when the collection is finished and we put looks together during two afternoons to really define who the Isabel Marant woman is.

'It's funny because she has managed to create exactly the image I wanted. I couldn't really do this before because as a designer you are always afraid to do something too normal. What we do with Emmanuelle is normal but still very cool. It's the easiest collaboration I have ever had.'

Marant's past few collections are testament to the strength of this partnership, and have solidified a look that has now made her copied everywhere from H&M and Zara to local boutiques in Causeway Bay. For her spring collection, inspired by travellers, her signature tops and dresses come in a sparkly lurex and other natural fibres, while worn-in tweed makes its way onto loosely structured blazers.

'You know when you travel you always think you are going to find cool unique pieces and you never really do? I wanted to build up my collection to be a mishmash of these influences. A pirate story came on top of this - sometimes I have got an idea in me but I cannot define what it is exactly - when I work on it, step by step the image becomes clearer,' she says.

While the collection still retains its Frenchness, it now translates to an international audience, thanks to Alt's high fashion styling.

That said, it's not just a cool new makeover that has contributed to the designer's mass appeal. A competitive price point - something she has always maintained from the beginning - means that her clothes are accessible to most women rather than just an elite few.

'Of course the recession has helped - the timing means that brands like mine are getting more attention. But from the beginning when I started, I always looked at how much my clothes would cost in the shop. I always feel a bit guilty putting too much money into something as frivolous as clothes - I hate this Kleenex fashion mentality,' she says.

'It's true that sometimes people didn't have respect for what I was doing because it wasn't expensive enough or luxurious. But Isabel Marant is cool luxury. I was always successful in a commercial sense - my shops work well and I was always very happy with this.'

For this reason, Marant wants to keep her growth slow and steady, focusing on more stores in Asia (she already has two free-standing boutiques in Hong Kong and her label is also available at I.T) and the US, where she has just opened a store in New York.

'I want to keep it small because I want to keep my style consistent to the original. I don't want to be forced to do things I want to do just for business' sake and to make money. At this point, you lose sense of what you are,' she says.

'It's only clothes after all. There are much more important things in life. I am a mother, I love my family and friends. I am very sentimental - I have had the same friends since I was five years old. Like my clothes, I keep them forever.'