Forever 21 America

Keep it in the family: Forever 21’s founder Do Won Chang with his daughters Esther and Linda, the firm’s creative director and head of marketing. Photograph: Observer

Forever 21 shoppers are young, grabby and fast, zooming through the Beverly Hills store on heels, their fingers ripping clothes from racks like birds swooping for fish. This is the American fashion chain run as a family business, the chain that, thanks to its "pile very high, sell very cheap" operation, has been a phenomenal success, with profits (in 2008) of $135m despite the fact that nothing it sells costs more than $65. This is the chain whose founder, Do Won "Don" Chang, is worth $1bn; the chain that, having conquered America and the Far East, is this month finally coming to London.

"Florals, Festivals and Feminine, " says 29-year-old marketing manager Linda Chang, the public face of the notoriously private family, pointing out trends as she strides among the bulging rails of playsuits and denim; her Chanel bag clangs against her Balmain-clad arm and Forever 21 jeans. There are fringed vests and one-shoulder dresses and slogan T-shirts, all under $20. "But it's not about prices. It's not a gimmick for us, " says Linda. "It's about value."

Stretching over 45, 000sqft, the Beverly Hills store feels vast and church-like, calm but for the customers, who rarely look at price tags before snatching down a dress, and who all emerge with swollen plastic bags. Standing outside, in the air-conditioned mall, they sigh. On YouTube, teenage girls upload their Forever 21 "hauls" – spandex tunics, jumpsuits, cocktail rings held too close to the camera; one of the most popular videos has had almost 2m views. Few bargain brands inspire such a following. And it's a brand that started humbly.