Time is ticking by and punctuality is rarely a priority within the fashion industry, especially when it applies to Irish journalists with planes to catch. As if by magic, the charming publicist "Rob" appears outside the restaurant decked in Yves Saint Laurent and is ready and waiting to escort us to Orla Kiely.

When we arrive at the Orla Kiely Head Office in south London, she is at her desk. She is dressed head to toe in her own range of clothing and greets us with a broad smile. As it turns out, she wasn't at a production meeting at all but a west end cinema screening of her son's school play. "His classmate's mum is involved with films so I think she pulled a few strings to get it screened." Pulled whose strings, I wonder . . . Mr Odeon's?

Fifteen years ago Kiely and her husband Dermott Rowan were manufacturing bags between their apartment in Toronto and a small factory in Nottingham. Kiely was working for Club Monaco, designing her small range of accessories after hours, and eagerly awaiting the whirr of the fax machine delivering orders. These days the Orla Kiely label is recognized all over the world, and her clothing and accessories are on sale in the most exclusive department stores, from Selfridges to Fred Segal.

Anyone who knows Kiely comments on her drive and determination. She has a reputation for talent and hard work, and when standing in her three-storey building in Clapham, it would be hard to argue otherwise. She is extremely slender and pale, not in the manner of the stereotypical fashionista, but rather as someone who prefers a sandwich on the run as opposed to a long, lingering lunch.

"I'm not afraid of hard work, naturally, but you aren't if you are doing something you love, " she shrugs. "If we have a deadline and I need to be here late or at the weekends then that's what it takes." Her husband Dermott volunteers at this point that they live conveniently close by . . . a five-minute walk to be precise, so she is never far away from home.

Unlike most interviews, Kiely is accompanied by her husband and public-relations consultant. We had hoped for a more intimate tete-a-tete, but it is clear Kiely prefers the company.

The conversation rarely moves beyond the 'Orla Kiely' brand, its past and particularly its future, and therefore any attempt to gather a sense of 'Orla Kiely the individual' is extremely difficult.

Kiely was brought up in south Dublin, and after finishing school she continued her studies in the National College of Art and Design. After graduation she moved to London and began working for the fashion label Esprit. Before long she was stationed in Dusseldorf, where she spent two very happy years enjoying life abroad and forging friendships that she enjoys today.

After a while, Kiely felt the grass was growing under her feet.

She realised she wanted to be more involved in the design and manufacture of the final product, so she resolved to go back to college and learn the necessary skills. She was accepted into the prestigious Royal College of Art in London where she completed an MA in fashion. Orla's graduation show proved to be one of the most important launchpads of her career to date;

her range of children's wear was selected to lead the finale and within days of her graduation she received a rather prestigious and important order.

"One of the buyers from Harrods had been at the show and liked my designs, so they bought the entire collection and asked if I could produce some more. So I did."

Looking back on what must have been a memorable day in her career, Kiely seems blase, although it seems more likely that what appears as apathy is actually shyness. She rarely does interviews and avoids the fashion social circuit, preferring family holidays and weekends away. She does not attend any of her own shows, preferring to stay in London and get to work on the next collection.

"I don't really like to go because I think it's better to let the people that are supposed to do the selling get on with it. I don't particularly want to push my own work; I'm not very good at that sort of thing because I just want people to like it straightaway, " she says twisting in her chair, and it is evident that even the thought of being in the spotlight makes her uncomfortable.

One day which stands out for both Kiely and her husband is an afternoon many years ago when they were browsing in the Terence Conran shop and spotted a chic Japanese girl swinging an Orla Kiely handbag under her arm.

"This was years ago, " explains Kiely. "At a time when we only made a very small number of tweed bags and before we designed our own fabric, because when you print you have to hit certain minimums, and we were operating a very small business. Anyway, this particular moment stands out because this girl looked really cool and I thought the bag looked good and it was a thrill, you know . . . she was the kind of customer we wanted."

This is all said very graciously. Although both she and Dermott are very proud of the Orla Kiely label, they are not in any way arrogant; in fact, they are extremely down-to-earth and self-effacing people.

While Orla might possess the creative streak and Dermott the business brain, one attribute they both share is cool, steely ambition. They intend to make Orla Kiely a worldrenowned brand much like the Paul Smith label. They take every opportunity to promote the range and seem to find very little fault with the fashion business or retail industry.

When I ask Kiely how her life has changed since she first started out, Dermott without hesitation interjects, "I don't think Orla has changed at all. She is just as creative and focused as she ever was." Kiely smiles and thanks him for the compliment, but what I really want to know is whether she is happy with her success or driven by a hunger for more. Eventually my perseverance pays off and she relents somewhat. "Well, I suppose we have a business, a proper business. We were busy then and we are busy now and of course, we have two children."

Their reluctance to talk about anything other than world domination does not seem to stem from a determination to shelter their private life, because they openly talk about their two sons, Hamish and Robert. They would just rather talk about Orla Kiely the label. They enjoy travelling (the latest collection was inspired by their summer holidays in the Alps) and often play cards with fellow Irish designer Paul Costelloe. Today however is particularly hectic because in addition to the interview, their home is being photographed by a New York interiors magazine.

"Two stylists flew in from the States yesterday, so the cleaners have been in and the kids have to be kept at bay, " laughs Dermott. "The magazine has organised some furniture to be photographed in the house which is either being sent here or to the house, I don't know which, but all in all it's been a bit chaotic."

This is not the first time their home has been put on display.

Another London-based magazine featured it very recently and after a quick glance at the glossy pictures it is not hard to see why. Their house is white-walled and airy but at the same time carries the cosy atmosphere of an urban, chic family residence . . . the kind of place the children of filmmakers spend Saturday afternoons. Orla Kiely has an eye for detail, whether it be the interior lining of her handbags and luggage or the striped inset tiles of her sittingroom fireplace.

They are most excited by their recent purchase of a piano, a beautiful golden-coloured instrument which they bought in the prestigious Bonhams auction house.

"It is just the sweetest little thing. I was so nervous because I had never bought anything at auction before and I was afraid I would get locked into some kind of bidding war, " says Kiely almost giddy. "I had the loveliest little piano man with me and he just said he would take care of it. I couldn't believe it, but I was the only bidder. I got it for £300!"

"The house really felt like a home once we had the piano delivered, " adds Dermott. Their eight-year-old son Hamish has shown a certain flair for music; for Christmas he received the sheet music for a selection of Abba songs.

"We don't want to push him, but he has shown a bit of potential, and once he got his hands on the Abba music he sat down and worked it all out, " says Orla with pride. "His favourite tune is 'Money Money Money."

Kiely is largely influenced by colour and prints, especially those that were fashionable during the 1950s. "I have always loved vintage wallpapers, their use of colour and scale just seems to appeal. I don't know if it has something to do with my childhood or what, but the look has always attracted me."

Orla Kiely prints are immediately recognizable. She has a number of signature designs that her customers return to over and over again. One of her earliest prints is frosted on to the windows of the Orla Kiely building. Dermott says that this particular pattern was in such demand that when they tried to rest it for six months "the customers in Japan were just screaming for it". Her flair for colour and pattern has been noticed by a number of high street stores such as Habitat and Debenhams, and in recent years she has worked with both companies to produce a range of diffusion lines in wallpaper and homeware.

The introduction of Orla Kiely to the high street is undoubtedly a giant leap for the brand which will now be accessible to a broader range of customer, particularly one that might not regularly perambulate through the shopping halls of Brown Thomas and Selfridges. But does this involve relinquishing a certain level of creative control?

Not at all, they both assert. "The contracts are very strict, " insists Dermott. "Orla has total and utter control, full approval."

"Yes, " adds Kiely. "We want everything that goes out to look good and to be true to what we design. I think I adapted well, although I can see why someone might think there must be some degree of artistic compromise, but there isn't because I just wouldn't do it otherwise. As a designer, I have to be inspired. Reproducing the same thing over and over again is not only boring . . . I just can't do it. When I sit down to work, the last thing I want to do is design something I have done before, regardless of how many people I think might buy it. In the case of the high-street designs, it's about adapting to the price points. That's the challenge and I like challenge."