As a child Nicky Kinnaird, the founder of the beauty chain Space NK, was determined that her name would one day be added to her family's chartered surveying business. She has arguably gone one better, by stamping her own initials on a store that is familiar on 58 UK high streets yet still manages to retain a certain cult status.

The trick, established with the opening of the first Space NK Apothecary in London in the mid-1990s, has been to focus on “hero” products from smaller, niche companies, such as Dr Sebagh and Kiehl's. This approach touched a nerve at a time when the growing interest in Botox and cosmetic surgery has made many women take skincare more seriously. Kinnaird says: “Women are asking what they can do without resorting to the needle or the knife, in terms of self-help and protecting their skin. We're educating people about how they can make the most of what they've got.”

Sales last year reportedly rose to more than £40 million. Last December she took on New York with four new stores in and around the city. And in a bold move, given the current financial gloom, she recently announced a deal with Bloomingdale's to open outlets in nine stores across the US.

Kinnaird, 44, doesn't look like a woman who sells £350 face cream. She brings to mind John Betjeman's Joan Hunter Dunn - suntanned (even with SPF 40), statuesque and outdoorsy, with bare legs, a sensible skirt and peach pumps. We meet in her tenth-floor Kensington apartment to discuss different cultures' attitudes to grooming, the influence of competitive sport on her character, and what it was like growing up a tomboy in Belfast during the Troubles. She loves tennis and golf, is “obsessed” with green tea and gravitates towards a particularly challenging form of yoga.

Kinnaird has said that she is no diplomat, and although she has a jolly laugh, she is mistress of the one-word answer, delivered in a measured Belfast accent. “Were you homesick when you left Belfast to go to Reading University?” I ask. “Yes.” “Do you meditate?” “No.” “Are you still close to your younger brother?” “Absolutely.” “Do you have children?” “No.” “Would you like children?” “What I would really like is a dog; a Wheaten terrier. The trouble is I travel too much.”

Kinnaird's flat is not unlike a Space NK shop: minimal, with glass-fronted shelves and neatly folded blankets on low brown sofas, the only splash of colour is a collection of frosted glass. She shares her home with a long-term partner about whom she won't say more than “he also travels a lot for work so we're ships that pass in the night sometimes”.

It has been said that the remarkable success of Space NK owes as much to Kinnaird's eye for a good site as to her relentless pursuit of cutting-edge moisturisers. Her career started in the male-dominated world of chartered surveying, and while she specialised from the outset in posh London fashion outlets her intention was always to return to the family business. But she soon realised that she was an urbanite at heart, and, aged 29, she opened the first Space NK in Covent Garden in 1993, selling fashion as well as beauty products. Within three years she decided to concentrate on beauty and added “apothecary” to the name.

Kinnaird believes passionately in the age-reversing serums and detox food supplements that she sells. She also drinks two and a half litres of water a day to keep her skin in tip-top condition but admits: “No matter what you slap on your face, if you haven't got the right lifestyle, diet, exercise and all the rest there is only so much a topical application can do.”

Without sport, she feels like a “caged bear”

Kinnaird is adamant that she would never have cosmetic surgery herself. “I don't have a judgment against anyone who chooses that route but it's not one I would go down,” she says. “There are too many people taking it to extremes; people who look as if their face has been trapped in a wind tunnel.” Since she practises what she preaches - and has inherited fabulous skin - she probably won't need to. She enjoys the occasional glass of good red wine (too much makes her sleepy), is fuelled by a constant stream of' green tea, and has always been madly sporty. If she doesn't exercise or spend some time outdoors every day she feels “like a caged bear”. Three mornings a week she plays tennis at 6am, Anna Wintour-style, with a coach, and she loves golf. She admits that she “probably does less on the relaxation front than she should”, and even the yoga she prefers - bikram - is extreme: practised in a heated room that makes you sweat buckets. Holidays are hardcore too. Once a year Kinnaird visits a health resort in the US, such as Ashram in southern California, which describes itself as “the smallest, roughest, toughest, leanest, meanest, sweetest health retreat on the planet”. It is there that Kinnaird - who was brought up a Presbyterian but is no longer a regular churchgoer - gets in touch with her spiritual side.

“It's a combination of yoga and hiking and is quite meditative because you could be the only person on the planet in some of the areas you walk through. That is actually quite a soulful experience in terms of giving you time to think about things.”

Kinnaird believes that growing up in a sporty, competitive family - combined, perhaps, with some Northern Irish grit - has shaped her. She is still fiercely competitive and proud of it. “There's a realism, probably. Whether that's from Belfast or just the family values that have been instilled in me that life does not come handed on a plate, you've got to work hard to achieve and what goes around comes around. We've always been pretty competitive as a family, in a good way.

“My younger brother and I used to try and beat the living daylights out of each other on the tennis court. I went to visit him in LA last week and even on the Sunday morning we were on the tennis court at 6am. He thrashed me, which was most disappointing. So the rematch is on for the next trip!”

Kinnaird plays down the difficulties of growing up in Northern Ireland during the Troubles. She had a “comfortable” upbringing in the suburbs of Belfast and played for all the teams at her girls' grammar. “You got used to the fact that if you went into the centre of town the place was cordoned off with security barriers and so forth. Being frisked and bag searches in every store were just the norm.”

Did she worry about her father commuting into the city centre? “It was the way it was; you didn't know any different.”

In any case the family escaped to a completely different life for three months every summer, in their house on Spanish coast. It was there that Kinnaird became obsessed by Spanish pharmacies and the “whole different mindset” around bathing products; she particularly remembers a delicious baby cologne. Although she was a “complete tomboy” who loved Action Man, the bathtub has always been her refuge.

The British mind-set has changed

Looking to the future Kinnaird has good reason to be sanguine about the credit crunch; Space NK has, after all, survived one recession. So while you might think the current belt-tightening would put people off pricy spa treatments and scented candles, Kinnaird will have none of it. She points to the numbers of men who are tempted into the Space NK spa in Notting Hill for a massage to cope with stress, and within months are having facials.

“In the credit crunch people are more inclined to cut down on their fashion purchasing, and buy a new lipstick or a whole new make-up look instead, because it gives them a fashion change much more cost-effectively,” she says.

“The British mindset - that you don't want to be seen to be spending time on looking after yourself - has changed dramatically.”

Beauty spots

29 Kinnaird's age when the first Space NK store opened in Covent Garden in 1993

£40m estimated turnover of Space NK last year

£350 most expensive product in Space NK: Chantecaille's Nano Gold Energising Cream

58 Space NK stores in the UK

£3.7bn value of British beauty industry

Source: Times database

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