FORGET Chanel No 5, Obsession, Eternity and Poison. Britain's favourite perfume is Anas Anas, and this is its tenth year at the top.

Despite the difficulties of ordering a bottle in Boots (not Anae Anae, nor Anayse Anayse, but An-eye-ees An-eye-ees, please), Anas Anas outstrips all its rivals, selling nearly twice as much as its nearest competitor. This translates into purchases worth around £16m last year; a total of 70 million units of Anas Anas have passed over the counter in this country since its launch in 1978. A 30ml spray of Anas eau de toilette costs £16.50.

The stuff is a mixture of lily, orange blossom, jasmine and rose, with Florentine iris, Virginia cedarwood, Bourbon vetiver and sandalwood. Its manufacturer, Cacharel, claims that Anas Anas is "the youngest of the classics", but in the same breath says it is "subtly evolving in the hands of its creator, Annette Louit, to remain in tune with changing social attitudes to express a sense of continued modernity." So, it's not only a perfume, but a neo-classical social statement.

Why is everyone wearing it? Odour expert David Kelly, a University of Wales chemist, isn't sure. "Virtually all perfumes have musk in, which smells like human pheromones. When women wear perfume they are putting on a surrogate man, but this one doesn't seem to have any musk in it," he says. He suggests the typical Anas woman is "emotionally ambivalent with extroverted mood tendency". She also "associates erotic perfumes with the concepts `light', `playful', `romantic' and `tender'."

Dr Kelly is right - there is certainly nothing aggressive or overly sexy in Anas Anas's pastel pink and green bottle. But part of its secret might be that it doesn't knock out bystanders at 20 paces. "It's a nice gentle smell - there's nothing to object to," said one male purchaser. "Everyone likes it, I can lay in a stock and give it to my wife, my sister and my mum."