When Cos opens its Dublin flagship in Wicklow Street next Friday, three years after its introduction to Ireland by BT2, it will house the complete womenswear, menswear and childrenswear collections. The London-based Swedish brand, part of H & M, which launched at the Royal Academy in 2007, now boasts 91 stores across 20 countries and opened a further 10 last year alone.

Its clean-lined, stylish basics in mostly plain colours and natural fabrics, but with points of difference in cut, detail and price, have made it a winner for women of all ages – and men too. Its success is also due to its ability to remain modern and off-centre without slavish concessions to trends, pushing new shapes while retaining utilitarian safety nets.

The spring collection based around the idea of ocean and reflected surfaces, for example, mixes innovative honeycomb knits, mesh fabrics and pearlescent finished cotton, with denim and poplin.

New colours include burgundy and emerald along with its more traditional greys, black, blues and white. Shapes range from longish summer coats with wide short sleeves in pale pink or lemon, to hourglass party frocks in stiff, shiny black polyester. Accessories are always original and inexpensive.

The woman fast tracking Cos’s rapid growth is Marie Honda, who has the rather strange official title of Brand Overall Responsible.

We meet at the brand’s modern headquarters off Oxford Street in London, in the former Dickins & Jones building – where she stresses that teamwork has been the key to its success. Of mixed Swedish and Japanese parentage, she grew up in a creative environment in Stockholm and originally trained as a seamstress and pattern cutter before moving to study at London College of Fashion and later London College of Printing. Since joining Cos as a menswear buyer, her rise in the company has been rapid.

“My diverse background has been an advantage,” she explains in her reserved, but friendly manner. “I am involved in all aspects of product development. Everything starts here.”

The in-house team of designers, buyers and architects comprises some 70 people who meet regularly to swap ideas. “Our customers are city people with an international mind-set who are interested in everything happening around them – in culture, art and politics – and we try to offer a collection for their everyday needs,” she says.

Dressed informally in low-key chinos, a black silk bomber jacket and a white shirt, she agrees that Cos has become particularly well known for its white shirts.

“We tend to revisit them every season, and make little changes to the details to keep them relevant and modern. We work a lot on quality and attention to detail. It could be a new silhouette, but the inspiration always comes back to art and design. As a team we always talk about what inspires us – art, architecture, lighting, sound – and we talk a lot about functionality, flattering fit and comfort.”

Modernity is a word that crops up frequently in her conversation. Though Cos was always associated with natural materials, better quality man-made fabrics now play an important role and “it is important for us to have innovation”.

A trench coat can be modernised with new technical fabrics, but at the same time she also points out that for winter, Cos will be using Harris tweed for coats.

Unfortunately Irish tweeds have not come under their radar nor are there any Irish designers on the team.

Honda, who is married with a two-year-old daughter, will be visiting this country for the first time for the official opening next week. With so many openings and so many disparate markets, her travelling schedule is a punishing one.

In the past few weeks she has been to Singapore, Milan and Dubai, but in a telling moment later suddenly remembered that she had also been in Geneva. After Dublin she will head to New York.

“We have the same collection throughout all 20 markets,” she says.

Many argue that an aspect of Cos’s success is its intelligent visual communication. Its magazines with their (often arcane) interviews with leading architects, designers and artists, contribute to its aesthetic appeal.

“It is an integral part of all of us and we are quite protective of it. I am never fully satisfied. I am quite hard on myself. I set high standards and expect others to follow the same,” she says with a smile.

Modest, understated yet sharp, she personifies some of the qualities that have made – and continue to make – Cos an affordable and coherent alternative to the directional big hitters of the international catwalks.