BY Cat Callender | 11 May 2008

Fashion mogul Jane Shepherdson Photo: REX

Jane Shepherdson has been dubbed the most important woman in fashion and the most influential person on the British high street. But her wardrobe is still a mess. Its contents are barely contained when the doors spring back, her crumpled clothes slung on to wire hangers (yes, wire, not even plastic) and her shoes thrown in a pile underneath. No colour-coordinated rows of pristine clothes or Polaroids on shoeboxes here. 'What? Euch, isn't that just what designers do?' says Shepherdson, recoiling at the thought that anyone would consider her so obsessive.

The former brand director of Topshop, Shepherdson has been credited with democratising style and changing the way we buy and wear fashion. In the mid-1990s she created such well-designed, style-savvy clothes it became de rigueur to wear high-street fashion. We take this for granted now, but back then women wore expensive designer labels or cheap high-street threads and never mixed the two. Under her auspices (she worked for the company for 20 years, leaving in October 2006), Topshop was transformed from a tacky teen store into a style mecca and addictive retail experience. After years of men ruling over a dull, poor-quality British high street, Shepherdson was the woman who brought about its renaissance. But she still considers herself one of the girls. 'I am. I'm very, very ordinary. I am just like millions of women.'

She's the least corporate executive you're likely to meet. Blonde, pretty and tomboyish, she says she feels like a footballer in a dress. Her hair is a low-maintenance bob. Her clothes are edgy but not alienating. There's nothing frilly or frivolous about her. She's 45 but looks ten years younger. Today she's wearing Chloé platforms, Topshop Baxter jeans and a grey and pink, splodge-print Marni top. 'Isn't it great? It's pink, too. Just to be awkward. Told everyone at Whistles, "I don't like pink."' She's referring to her new job as chief executive of the small fashion chain. It has a bright-pink logo. You suspect that's one of the many changes she will be making.

Still, we're not here to talk wardrobes, Whistles or even Topshop. We've met to chat about Shepherdson's unsalaried work with Oxfam - how she's transforming the charity's dowdy retail spaces into ethically conscious fashion destinations.

She has chosen the interview location: her Georgian townhouse in Islington, north London. It's thoughtfully furnished but not at all precious. Salvaged wooden theatre seats line the hall. A haunting photograph by the legendary war photographer Robert Capa hangs on the wall. Celia Birtwell illustrations decorate the downstairs loo. Mementos of her travels - a colourful bust from India, a wooden sculpture from Brazil, a giant map of South America - are peppered throughout the house.

Shepherdson was instantly receptive to Oxfam's appeal for help. 'With the usual bumph that they send through there was a handwritten note saying, "I hear you've got a bit of time on your hands." I thought, "Quite cheeky, but good for you." So I phoned them up.' She wasted no time telling the folks at Oxfam its stores were behaving like charity shops not retailers; that they were missing a trick by not capitalising on the growing interest in ethical and sustainable fashion. 'We looked at it as we would any brand: who's the customer? How can we please her and give her more? How can we attract more customers?' The results of her Midas touch have been unveiled this weekend at Oxfam's Westbourne Grove store in west London, with more to come over the next two years.

In addition to a brand-new, sustainable shop-fit, the stores will stock a host of sustainable fashion labels and rebrand their second-hand clothes as recycled fashion. Shepherdson has also set up an initiative with some of the bright lights from the London College of Fashion. Its most promising students have designed items of clothing created from a mix of environmentally friendly fabrics and restyled second-hand clothes and textiles. Alongside this, the charity will hold an eBay auction for one-off cr eations by hot British designers, such as Giles Deacon (who reworked printed 1970s curtains and chenille bedspreads) and Christopher Kane (who used old evening dresses spanning several decades as his raw material), as well as Henry Holland and Jonathan Saunders.

Bubbling beneath Shepherdson's blonde chuckles and fashion chatter is an undercurrent of confidence and quiet self-belief. She's incredibly charismatic and self-assured, kicking off her platform sandals to reveal bare, unvarnished toes mid-interview. There's an electric keyboard in the sitting-room. When I ask her if she plays she says no, but jumps up and bangs out a rendition of Chopsticks with gusto (the keyboard belongs to her husband of ten years, Barry, a lawyer whom she met on a blind date).

Although she's widely credited with starting the ethically questionable, fast-fashion phenomenon that now pervades the high street, Shepherdson denies taking the voluntary adviser post at Oxfam to assuage her guilt. 'But I never really saw Topshop as doing that,' she says, slightly testily. 'We set out to create something at a price that a lot of people could afford, something that had a credibility and an attention to detail. We never set out to create throwaway fashion.'

In fairness, Shepherdson's commitment to ethical fashion does not seem to be a flash in the pan. At Topshop she helped investigate labour exploitation among suppliers and, since leaving, has criticised the quick-fix nature of high-street fashion, saying it 'was getting a bit boring' for people to find their wardrobes full of 'cheap rubbish'. But she is conscious of the fine line she's treading by making such comments. 'I love clothes and I try and create beautiful clothes for people to buy. So it would be extremely hypocritical of me to say we shouldn't be buying them. The only way I can make it right in my head is to say, "Well, at least let's make sure the process is as fair to everyone involved as it can be."' Does she now consider herself a green crusader? 'No, I'm not. No, I'm not. I think a lot of people will be looking at me saying, "Who the hell does she think she is?" And I don't think I am anything. But if getting a bit of publicity is helpful for Oxfam, then it's worth doing.'

Born in Bristol, Shepherdson comes from a family of academics. Her mother is a biochemist, her brother an animal behaviourist and her sister a writer. Her father was a maths professor at Bristol University. Shepherdson spent her teenage years customising clothes in her bedroom and designing the odd outfit for her mother. After attending Clifton High School she moved to London aged 18 to read business studies at North London Polytechnic. From there she went to Topshop, where her first big break was in the late 1980s when she bought a job-lot of tank tops at a time when they really weren't cool. Her instinct proved right and has barely failed since. In 1999 she took over as brand director. The company had an annual profit of £9 million. After six years it was racking up more than £100 million. No other brand director has been so successful.

Shepherdson says she owes this success to her refusal to sell something simply because it would sell, insisting instead that they create clothes that were as exquisitely designed as possible. 'I took over a T-shirt range and I thought a lot of it was terrible. And I just said, "Yeah, we would probably sell that big, wide, pastel-stripe T-shirt, but I'm not buying it because it's disgusting. Hate it." Nothing I enjoyed more than saying that. I used to do it a lot as a buyer. I felt I had a duty. If you really care passionately about giving people the most beautiful thing you can create for them, then they'll come back.'

Eight months before she resigned Shepherdson told me that when she first started bandying about her master plan it flew against the received retail wisdom of the time. 'Everything was based on retailing formulas. You know, all the crap talked by men in retail - formulas and percentages. To me that's utter nonsense. That's not how women shop. You don't say, "Oh, a percentage of my wardrobe will be this and a percentage that."'

Why then, I ask her today, are men still ruling the retail roost? 'Generally, they are more competitive. They want to get to the top more than women do. Not more than I do, but more than most women do. Their style tends to be a bit more aggressive and a lot of women don't necessarily want to fight to the top.' Was it a fight for her? 'Yes. You have to be quite bloody-minded. You have to stick to your guns. You have to be prepared to be quite aggressive and confrontational.'

She believes women should be running the women's clothing stores on the high street but acknowledges the glass ceiling is still a fixture there. Perhaps with the likes of Kate Bostock being tipped to become M&S's new chief executive when Stuart Rose steps down in 2011, this might soon change? 'It would be a really good thing because I think [women] have a more instinctive understanding of what women really want. I know how they shop because I do it myself.' She pauses and laughs. 'If I was a man, I'd have to think, "I wonder what a woman would think about this?"'

She has no problem calling herself a feminist and finds it easy to square her politics with her passion for fashion. 'Designing beautiful clothes is like creating or designing anything that is beautiful. I don't see any issue with that at all. I like to look great but that doesn't mean that I am going to lie down and get trampled over. I'm not going to go out without make-up on and burn my bra.'

She won't be drawn on the sensitive subject of her previous boss, the multi-billionaire owner of Topshop, Sir Philip Green, with whom she had a notoriously difficult relationship. You can't blame her for her silence; having resigned 18 months ago she must find it tedious still to be asked the Kate Moss question . (Shepherdson has consistently denied that her resignation was linked to Green signing Moss to create a collection for the brand and has said, 'I find it embarrassing that people think I left over a row about a supermodel. It is a shame that people think I am that trivial.')

Instead, she chats about her gap year between Topshop and Whistles. Rather than migrate to a rival retailer, Shepherdson went travelling with her husband in South America and rode horses in the wilds of Patagonia. But, most importantly, she stopped shopping, buying and thinking about clothes. 'I didn't go to the high street at all. I was kind of burnt out. I just thought, "I can't be bothered."' Instead, she became a non-executive director of People Tree, the Fairtrade ethical fashion company. 'I certainly felt that anything that I did do would have to be in my value set. But I also didn't want to do anything where I would have to compromise or sell out in any way,' she says tellingly.

Shepherdson's takeover of Whistles was announced last February. Together with key members of her former team at Topshop, she is reinventing the upmarket high-street label. During the 1980s and 1990s Whistles was the place to shop but, more recently, it's been languishing in the retail doldrums. She intends to put ethics at the heart of the brand: 'It's a priority', she says.

Her first Whistles collection is due out in early autumn. Reluctant to disclose any details, all she will say on the subject is that she wants to offer beautifully designed pieces that don't slavishly follow the trends. 'It feels like being reborn. Suddenly you can run a business in the way you think is absolutely right in every way. Hopefully. And, hopefully, it will be successful.'

She pauses before delivering her parting shot with her trademark bravado, 'What have I got to lose? My money? My reputation? Well, it's not the end of the world, is it?'