Rich source of inspiration

American photographer Tina Barney works like an anthropologist. Her camera is her notebook, her subjects are members of East Coast America's and Europe's super-rich tribes, captured informally in their domestic habitats.

This exhibition opens with Barney's late-Eighties photographs of her extended family - grooming, lounging and feeding. They are large and appropriately sumptuous pictures, flooded with flash for intense colour saturation and packed with chintz - it's her signature style.

But more than mere glossy family portraits, there is a tension underlying the relaxed family scenes: Barney subtly expresses and explores the relationships between siblings, parents and children, and places herself inside the frame in several situations, talking and ignoring the camera, while also controlling it.

The question hovering intriguingly over the whole show is how much collusion existed between the photographer and her subjects.

Barney's subjects are typically posed imitations of the traditional "society portrait", similarly packed with the props - furniture and paintings, heirs, jewellery and clothes - used by their owners to judge each other.

In 1996, Barney visited Italy and, staying within the same tribes, began The Europeans project. Interesting contrasts emerge in attitudes and lifestyles, most obviously the relative decline of formality in the US. The transition is well illustrated in The Card Game, 1986, where two boys in shorts play cards with a grandad.

The European subjects and their surroundings reflect a long ancestry and continuity of line. Barney exploits the objects to make that point - The Ancestor, 2001 (England), shows a butler standing behind his "master" who is in front of the painting of an ancestor he closely resembles, while The Brocade Walls, pictured above, 2003 (Spain), wonderfully choreographs family hierarchy through the flourish of a matriarch's hand towards her daughter, who is looking away.

With the German and Austrian subjects, traditional elements blur the lines - clean, classless girls appear in dirndl skirts, and a Bavarian couple walk in hunting tweeds. In Spain, Barney broke her pattern and left her circle entirely to portray a Matador and a Flamenco Singer, but the results lack bite. This seductive show erases any inverse snobbery and feeds our insatiable voyeurism.

The Europeans exposes a habitat visible mostly through controlled magazine portraits and paparazzi shots. It creates a feast for relationship analysts, and satisfies their curiosity about the lives of these rare species - and how they relate to each other (coolly, in the main). The sneering arrogance of two cherry-lipped Students (Eton or Harrow) symbolises the complexities of Europe's class system which this American has bravely attempted to untangle.

Until 2 May. Information: 0845 121 6878.