Comptoir des Cotonniers is the British high street's French quartier, a home of Île de Ré chic, that carefree off-duty elegance achieved only by hours of preparation. This look is exemplified by the chain's advertising, which features mothers and daughters recruited from the better-looking end of its clientele.

The images of this campaign are intended to underline the clothing's intergenerational appeal: the grey patent parka (£111) is equally sharp on the 16-year-old and the 46-year-old. But, while admiring the style of models such as Silvia in the full-grey skirt (£98) and her offspring Claudia in the flowery dress (£137), you can also feel exhausted at the thought of the dedication necessary - at any age - for such insouciance.

Surprisingly, the British seem to feel equal to the challenge of meeting these maintenance standards. Demand for Île de Ré chic, as worn on this resort popular with the hip Parisian professional classes, means Comptoir des Cotonniers, which already has nine UK stores, is opening several more outlets this year. Currently there are a total of 333 stores in France, Japan and elsewhere. But, then, Fast Retailing, Comptoir des Cotonniers' Japanese parent, is ambitious for its children, who also include Uniqlo, a growing name in low-priced, but fashionable leisurewear. The aim is to create a dynasty to rival H&M.

In this endeavour, Fast Retailing has been helped by Carla Bruni, the honorary ambassador for appropriate-to-the-occasion French dressing now once more in the ascendant, thanks to her way with a Dior suit. Comptoir des Cotonniers caters for those off-duty occasions when a Dior suit will not do.

On Monday morning, the store in South Molton Street, London, a mini-boulevard off Oxford Street, was ready to kit you out in shades of greys, blues and creams for weekends and holidays, in wide-legged trousers (£107), leather jackets (£312-£398) and pleat-fronted smock dresses (£107-£116) - to be worn belted so that everyone knows that you follow the diet in French Women Don't Get Fat.

Marriage to a Frenchman has made Deborah, my colleague and Chain Reaction companion, familiar with the Gallic doctrine of wise investment in the wardrobe. Yet she was still taken aback by the prices of such things as the vests (£34-£66), which might be enough to send some customers to the Uniqlo five minutes away.

But she and I lingered. Comptoir des Cotonniers is the sort of shop that makes you want to study every single thing and then go home to get rid of every under-achieving piece of clothing that you own, exactly as French mothers counsel you should do every season. You return to make considered purchases to enhance the pieces that remain. For many of those who follow this principle, the grey platform T-bar shoes (£150) will be a top choice.

The links in the chain

Fast Retailing (Comptoir des Cotonniers' owner) made a

net profit of 28.6 billion yen (£1.43 billion) on sales of

316.4 billion yen in the half-year to February 2008.

Retail is detail

Layout: white, bright, but anonymous 6/10

Staff: knowledgeable about the stock, and proud of it 7/10

Changing rooms: really clean 8/10

Website: no online shopping 7/10

Overall score: French glamour without tears, but at a cost 8/10

Explore Women

• Fashion

• Beauty

• Diet & Fitness

• Relationships

• Families

• Celebrity

• The Way We Live

• Horoscopes

Times recommends

• Are eldest children really a cut above?
• Peaches Geldof: censored
• Top 10 style-setting films of all time