Kate Moss has done it for years. Recently, the Duchess of Cambridge has been doing it too. Yet only very few women possess that particular combination of public profile and personal style that inspires other women to buy their clothes.
IN PICS: Fashion's big sellers
Trying to work out which women truly have that knack is tricky. When trumpeting a sudden rush of purchases of an item worn by a well-known somebody, companies will only describe sales increases in impressive-sounding percentages rather than potentially measly units sold. There is so much hoo-ha about the Duchess that at least some of it (see below) must be trumped up.
But...
