It was inevitable that such power would be commercially exploited by the advertising business. Cigarette sales were given a boost when picture cards of stars were introduced into packs. But it was during the 1930s and 1940s that the top female stars of the Hollywood studio system were used most fully. They endorsed a wide range of merchandise, from soap — “Veronica Lake owes her flawless complexion to Lux” — through beauty — “look lovely for hours like Rita Hayworth, thanks to Max Factor” — to cigarettes — “Lana Turner chooses Lucky Strike, the brand that satisfies”. From Elizabeth Hurley to Isabella Rossellini, female stars continue to do so today. Handsomely paid, their job is to harness our desire for the unattainable — the perfect complexion, the ultimate hairstyle, the ideal dinner party — by suggesting that if we buy the right products, the stars will bring everything within our grasp.

But there are different approaches to advertising, as Individuals, a new book of celebrity portraits from Gap’s advertising archives, makes clear. The Individuals of Style campaign was launched by the company in 1988 as a ground-breaking exercise, with the emphasis on personalities. The chosen celebrities were photographed wearing different brands together with Gap in order to reflect the way we all dress — for example, a Gap T-shirt with a mix of other favourite clothes. Among those who have been photographed for the campaign over the past 18 years are Miles Davis and Spike Lee in the 1980s, Jerry Hall and Veruschka in the 1990s, and Carmen Cass and Helena Christensen in the Noughties. The Gap campaign is a roll call of iconic figures in music, film and fashion, shot by photographers of the calibre of Herb Ritts, Annie Leibovitz and Steven Meisel. And who wouldn’t smile for their cameras?

Individuals: Portraits from the Gap Collection (£20 Dorling Kindersley) is published tomorrow, available from Gap stores and book shops. All profits go to Red. Individuals exhibition at Colette, Paris, until October 28, and at the National Portrait Gallery, WC2, from February 14, 2007

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