What I love is this idea of a wardrobe," says Phoebe Philo, "the idea that we're establishing certain signatures and updating them, that a change in colour or fabric is enough. I do think the world doesn't need many more frivolous bits and bobs that end up left in cupboards or landfills."
She is talking about Celine, the French fashion label she took over in 2008 in a blaze of publicity, and transformed into a global phenomenon almost overnight. Until Philo's arrival, Celine had been floundering. Under Michael Kors, who stepped down in 2004, it was beloved by the monied New York professional. However, despite the brand's longevity - it was founded in 1945 by Celine Vipiana - it lacked a heritage to rival the more well-known French fashion houses. There was no trademark tuxedo or pussy-bow blouse to think of, for example, nor anything remotely as famous as Dior's New Look line skirt or Chanel's boucle wool suit.
"Some of the brands I respect most in the world have that core," Philo continues, "so I'm proud that people are now coming back and asking for the same thing."
With that in mind, and just a little over two years after Philo's arrival, the Celine look is already instantly identifiable. There's the collarless white shirt with ultra-long cuffs designed to be worn with tails trailing behind; the fluid, wide-legged trousers; the sleeveless dress that stands away from the body as opposed to clinging to its curves; the crepe jumpsuit, and several highly covetable bags.
"There are elements that have become classics to us. They sell really well. The response has been good. Trousers, tailoring, shirts, skirts, 'category pieces'.
"I hate these kinds of words but they've sort of become [she pulls a face] staples ..."
It's safe to say Celine is today the ultimate stealth wealth tag for the intelligent, modern woman to see and be seen in. And more impressive still is the fact that Philo doesn't rely on anything obviously publicity seeking or high-impact. Instead, the appeal of her work lies in its apparent simplicity and unassuming, no-frills approach. This is an aesthetic aimed squarely at a discerning, confident customer who would rather not parade obvious fashion credentials and for whom both modesty and discretion are of prime importance. And, for that, it is a breath of fresh air.
The Celine autumn/winter pre-collection, which goes on sale this month, is very much a variation on a similar theme. "It's pretty masculine. That's how I dress and I think it's quite liberating for women not to have to be so preoccupied with different silhouettes, with different things," Philo says.
The powers that be behind the LVMH-owned Celine courted Philo for some time and have been unusually flexible where any working arrangements are concerned. Philo's position is pretty much unique among fashion designers. Celine is based in Paris but she lives and works in London. She has suitably grand, though certainly not ostentatious, offices in a Georgian townhouse in Cavendish Square and the technicians who produce her designs travel from France on a weekly basis to show her any prototypes or work in progress.
Philo insists on a reasonable working day. For the most part she makes sure she's home to put her children to bed each night - she has two by her long-time partner and husband, the art gallery owner Max Wigram.
"I have a fantastic team and it's much easier having children, because that creates a natural limit. If I have a good time with them before they go to sleep, it's worth everything to me."
When, in 2006, Philo left Chloe for "personal reasons", the label was at the height of its success. She arrived there in 1997 as Stella McCartney's first assistant and when sales were on the floor. She was made creative director in 2001 when the latter went into partnership with the Gucci Group to launch her own label.
It was widely understood that the secret of Chloe's turnaround had been Philo's ability to identify what the label's young customers might like to wear even before they'd realised it for themselves. When she took to the helm, that fact was driven home. Boyish tailoring and sweetly flirtatious voluminous tunics, the money-spinning Paddington bag with its ultra-cute and chunky padlock, equally clunky wooden-heeled shoes, butterfly pendants and more, sold like the proverbial hot cakes. Philo resigned in a genuine and openly expressed bid for a well-earned break.
Nonetheless, she found herself in the fortuitous position of becoming hotter property still as speculation mounted over what Phoebe might do next.
Visitors to Celine's London premises are greeted by a seascape by French photographer Marine Hugonnier and a twinkling Tim Noble and Sue Webster light installation that reads, "forever". Philo's office, on the second floor, is dominated by huge windows and and a very high ceiling.
The designer is wearing a masculine white shirt and cropped black trousers, men's shoes which appear to be several sizes too big for her, and a shrunken, black leather biker jacket, with articulated quilting at the elbows that she says she bought in Japan. "I wear it all the time," she laughs. "It's taken on my body shape." Her sandy blonde hair is pulled back from her classically beautiful face, her pale, blue eyes are huge, her cheekbones chiselled and her skin is as nature intended - entirely make-up free. She says she looks "a bit butch, I suppose".
Philo, it has been said before on numerous occasions, is the best possible advocate of her own designs. Also oft-repeated: she is clearly in possession of the best possible taste. In the past, she has been described as aloof and even cold, but that is unfair. Philo is wary, clearly, but disarmingly straight-talking and not one to suffer fools. Given that interviews with the designer are extremely rare, it's safe to assume she's ill at ease in the presence of journalists. Certainly, her reluctance to talk about her private life is palpable.
"I'm not like that on purpose. It's just about my comfort zone," she says, not unreasonably.
Philo doesn't tweet, blog or communicate via Facebook. When she shows her collections, her backstage area isn't open to the media.
In an age where fashion designers are expected to step out on the red carpet alongside the people they are required to dress at every given opportunity, Philo refuses to play that game. In light of the media circus that the fashion industry has become, that is refreshing - as ultimately forward-thinking as her clothes.
"Do you hate being interviewed?"
"I just feel it's really unnecessary."
"But it's a requirement of the job?"
"It is. But I think that the clothes say it all much better than I can. I always find it strange after a show when everybody comes backstage and says: 'What was it all about'? It's like: 'You've just seen it. What do you mean?' My instinct is to say: 'What did you think? What did you get from it?'
"To me, the show is quite a complete story. There's nothing more for me to say and, anyway, it doesn't matter what it was meant to say. It's out there. It can be whatever anyone watching it thought it was, surely."
To sum up, Philo is deliberately - and uncompromisingly - media unfriendly and, though that might frustrate those queuing up to gain access to her, it has served her well. Despite the zeitgeist, history has proved that leaving at least something to the imagination has never done anyone any harm.
"I do like the idea of women not showing too much," she says, "of them being quite reserved in a way, and quite covered," and she might just as easily be talking about herself as a person as her designs for Celine.
"The only way I can do it is by being completely honest. Everything I do here is authentic to me and I do it as if it was my own."
Here's what is known about Philo. She was born in Paris and grew up in West London. She was bought her first sewing machine at the age of 14.
"I never had a massive desire to buy clothes," she says. "I liked to customise the clothes I already had or was given when I was younger. If I didn't like them that much, I made them how I wanted them to be. I don't really like shopping. I don't get a great feeling out of it."
After school, Philo completed a foundation course at Wimbledon College of Art before applying for the fashion BA at Central Saint Martins, from where she graduated in 1996. She was, she has said, especially interested in the fashions of the early 1990s, a fact that is still evident in her aesthetic to this day. Her ad campaigns for Celine are shot by Juergen Teller - among the most ground-breaking photographers of that era - with a comparative lack of gloss and a focus unflinchingly directed towards the product.
"I guess that period informs me because of my age," Philo says. "When I was growing up, that was what magazines and books were all about. That was how people on the street were dressing. When I go through old i-Ds or other magazines, they bring back that time when I was 20 and I remember that image or soundtrack or holiday. It brings back a nice familiar feeling."
There are subtle references to the 1970s, too. "That comes back to nostalgia as well," she says. "I was born in 1973, during the Vietnam War and the first wave of feminism, and I have a love/hate relationship with that time. I feel that, politically, a lot was going on, but there's a frivolity to some of the images of women during that period that I don't really identify with."
Until she left art college, Philo was unaware that it was possible to make a living as a fashion designer.
"I've always been interested in the way people look and dress and very opinionated about what I choose to wear, but I had no idea it could be a profession. Thank God.
"I feel now people are almost too aware and, for students, that seems like a heavy load to carry. I felt very free for not knowing. I did drawing and sculpture, a bit of everything, but very much enjoyed the time I spent doing fashion. Then I discovered it was possible to specialise and I worked hard on my portfolio to get into Saint Martins.
"It wasn't until then that I knew. I was 18 and that's quite old when you think that, today, probably even 12-year-olds are aware you can become a fashion designer."
Just a year after leaving Saint Martins, she went to Chloe with McCartney and the rest is history. That is until September 2008, when, with at least a degree of fanfare, it was announced that Philo would be designing Celine.
Bernard Arnault, the chief executive of LVMH, hosted a celebratory lunch in Paris and brought in a new president and director, Marco Gobbetti, responsible for overseeing Givenchy's reversal in fortune, for Philo to work alongside. Pierre Yves Roussel, CEO of LVMH's fashion division, told Women's Wear Daily: "By giving her [Philo] Celine, we're allowing her to express her vision. For Celine, which is a bit more grown-up as a brand, the fit is very good in terms of her style, her personality and where she is in terms of development."
Philo herself, spare and to the point, said only: "In the current climate, customers are looking for something that will get them interested and excited about buying again. I want to create clothes, shoes, bags and accessories that are relevant to right now - modern exciting designs that women will desire and appreciate."
And, true to her word, that is just what she did.
Celine started life as a made-to-measure children's shoes business that soon grew to encompass women's and children's shoes and accessories. The company began producing ready-to-wear in the 1960s, at which point it was known for classically bourgeois designs intended to stand the test of time. In 1996, it was bought by LVMH and, a year later, the aforementioned Kors took to the helm as designer. After his departure, two consecutive and comparatively low-profile designers failed to breathe new life into the label.
"I hadn't ever thought much about Celine before I was approached," Philo says now, "but then I looked at everything they were doing and it felt very irrelevant.
"Historically, the bits of Celine I knew from researching, generally over the years, were typically Parisian - a pleated skirt, a silk blouse and a blazer. And I quite like the conservativeness of that, that Parisian chic, that conservative woman. Bourgeois. A bit saucy. That's the element that I thought was intriguing and wanted to carry forward."
When the approach came: "I was heavily pregnant with my second child and LVMH contacted me to find out what I was up to. I remember having this huge tummy.
"We agreed it wasn't the right time to go into details but I said I was looking at going back to work at some point. So, I had my baby, and I think when he was four months old and I was ready, the conversation began again."
In the first instance, discussions were about the creation of a completely new, eponymous brand. "We looked at a business model for that. We talked about the products I wanted to do and the vision I had for it. And then Celine came into the picture. LVMH seemed very happy to allow me to do everything I would have done for my own label there, basically giving me the same amount of control, and it just felt right."
For the publicity-shy Philo, it couldn't have worked out more perfectly. "It's never been important to me that my name is above shop windows," she says, "and I get a lot of comfort out of having something I can stand behind. Let Celine be the name and the front of it, and I just quietly come to work every day and get on with it. It's nice. It fits."
It is not insignificant that Philo's first runway collection for Celine was shown in October 2009 and in the midst of the worst economic downturn since the Great Depression. With sales in luxury goods plummeting worldwide, the streamlined, neutrally shaded, and embellishment-free collection she showed on the Paris catwalk was very well judged. With a view, perhaps, to contextualising this aesthetic, Philo was immediately upheld as at the forefront of "the new minimalism", although she herself has little time for such monikers.
"What does that mean?" she asks. "All I ever said was that it was clean, stripped back and reduced - and that's not the same thing at all.
"Of course, I was reacting to the world. I'm a human being. My eyes are open. I try to have my feet on the ground. I guess I'm informed by lots of things, but it wasn't a political statement. It wasn't anything to do with the recession. It felt right. It was what I wanted to say."
Still, the subtlety and relative sobriety of Philo's vision, and its focus on quality over and above quantity has struck a nerve. "The fabrics we use are the best," she says, "and I'm fairly adamant about that. The emphasis is also on perfecting the cut. That's something I spend a lot of time on and, when I get it right, I feel very satisfied. The atelier is mainly French and they've come from the best houses and the craft they've learned you can't find anywhere else.
"I absolutely love fashion. I love doing new things and finding ways to swerve in a different direction. But one of the reasons why I try to use fabrics and cuts that don't go out of fashion is because I like the idea of women buying the clothes and then ... I don't know what the word is ... cherish sounds over-emotional for a relationship with a piece of clothing ... but for a woman to feel proud, satisfied, comfortable and powerful in them, to wear them and get on with their lives."
Finding the balance between moving fashion forward and establishing a timeless signature is probably the single most difficult challenge for a contemporary designer and Philo is well on her way to achieving it.
The interview's over and for the first time since it began, Phoebe Philo leans back in her chair and relaxes.
"Shall we have a fag?" she says.
* Celine is available in New Zealand at Scotties and DFS Galleria.