Rihanna at London Fashion Week

For the thousands of young fans who packed New Oxford Street in central London on Saturday night, there was only one fashion designer who mattered – Rihanna.

The pop singer unveiled her first collection for the British retailer River Island, for which the British press has reported she is being paid roughly $1.2 million, at a cavernous club space jammed with revelers, a few curious members of the fashion press and the occasional local celebrity (including Ms. Delevingne, who sat in the front row, dressed in an Adidas hoodie, denim hot pants and thigh-high boots).

This, of course, was not the first dip into the fashion pool for Rihanna; she had already created two collections (largely of T-shirts, jeans and a leather jacket) for Emporio Armani jeans, with Giorgio Armani telling the press, “Rihanna is a great artist.” More recently she told interviewers at the Grammys that she had partly collaborated with Azzedine Alaïa on the custom-designed flowing, crimson gown she wore to the awards ceremony, saying he had showed her several designs before she picked the one she would wear.

stage; the models strutted out to the accompaniment of rap songs of which roughly every third word is unpublishable here. The clothes, designed in collaboration with Adam Selman, who has worked with the singer on her tour costumes in the past, were body-hugging and flesh-baring with even the modest cover-ups featuring some elements of see-through design.