None of this will come as any surprise to seasoned cosmetic watchers, who take it simply as confirmation that "the lipstick index" continues to work. Coined by Leonard Lauder, chairman of Estée Lauder, the term describes the inverse relationship between global economic performance and cosmetic sales. Put simply, when times are tough, sales of make-up, specifically lipstick, soar. It was certainly true in the Great Depression of the early 1930s, when US industrial production halved while sales of cosmetics boomed. The same thing happened in the subsequent economic downturns of 1990 and 2001, when the cosmetics industry was obliged to take on extra workers to cope with the increasing clamour for face paint. Now it seems to be happening all over again.

The phenomenon is, of course, startlingly counter-intuitive. When money is tight the first thing sensible people do is cut back on any expenditure which cannot be classified as an essential, like food, heating or children's shoes. By this analysis, lipstick sales should go tumbling to the very bottom of the shopping list. Psychologists, however, posit the alternative view that, when times are hard, lipstick is reclassified in the household budget from an "essential" item to an "affordable luxury" (it tends to be women, after all, who are in charge of domestic spending). While a new dress from Prada, at £750, becomes out of the question for any rational person, a lipstick from Yves Saint Laurent, or even Chanel, is only going to cost £20.

What's more, for that £20 you don't just get a glorious slash of vermillion, rose or poppy to light up a face made pallid by winter weather and late-night poring over bank statements. What you get is nothing less than a little cache of feminine mystique. For lipstick, more than any other cosmetic, represents a kind of heady vibe that is eternally female.