London in this exhibition is a city of mud and puke. Leon Kossoff's and Frank Auerbach's cityscapes have the cloacal chaos of a world born rotten. In his magnificent, abject Man with Dog, Francis Bacon shoves your face even closer to the muck, to the level of a dog sniffing turds on the pavement.

Truth, reality, the facts of modern horror - Art in London in the 1950s was certainly engaged. The only argument was about the nature of that engagement. Social Realist painters such as John Bratby, championed by the critic John Berger, addressed the facts of urban poverty; they were denounced by Bacon's ally David Sylvester, who coined the phrase Kitchen Sink to dismiss lumpen factuality. Bacon's modernism was loftier in its misery.

And yet oddly, the vision of the city that drags you down to the level of Bacon's wretched dog in this exhibition is shared by realists and modernists alike. Edward Middleditch's Pigeons in Trafalgar Square is a kitchen sink anecdote that slips into sublime horror. Bratby's The Toilet is not a million miles from Bacon's world either, or Lucian Freud's. Even the futuristic speculations of the proto-pop Independent Group have an apocalyptic jaggedness.

However you cut it, the bread of life in postwar Britain was stale and furred with mould, with artists recording the war-scarred urban landscape, the colourlessness of a rationbook society. And then magically, at the end of the 1950s, colour arrived from America. If that sounds simplistic, it is. This exhibition does not transform our sense of the decade as a miserable morning in a smoky caff between the Dunkirk spirit of the 1940s and the love-in of the 1960s; a cliche, yet everything in this show confirms it. It certainly shapes the presentation of early pop art; even the seminal show This Is Tomorrow seems to sink into the brown sludge.

Fifties artists were not witnesses to any absolute truth about the modern world; the rancid street life observed out of a Soho pub at three in the afternoon was not the final truth of existence, but the version of the city they loved and invented. This show is not a completely convincing cultural history, but it does give you a seductive dog's eye view.

· Until April 14. Details: 020-7638 8891.