An American Experiment: George Bellows and the Ashcan Painters, National Gallery, London

Ho, for the critic's life.

Dare to say that you would rather not see the work of Norman Rockwell – a fine graphic artist, but not a fine artist – in a venerable London public gallery and you will find your in-box writhing with shaken fists. Claim that George Bellows impaled kittens on bayonets and you will not hear a word.

Bellows, a genuinely fine fine artist and eminently worth his current small show at the National Gallery, is hardly known in Britain. Insofar as he registers with most of us, it is as a member of the American Ashcan School, a movement named for its taste in urban grime. Close your eyes, think of Bellows, and you will see New York fire escapes c1912, washing lines strung across alleyways, and ladies of ambiguous virtue sitting on front steps.

Which is to say that the Ashcan School was, in terms both of date and interests, the rough equivalent of our Camden Town Group. If Edward Hopper is its best-known member – Ashcan membership was always loose-edged – Bellows was its most uncompromising. His art has nothing of Hopper's mournful poetry. Pictures such as Cliff Dwellers (1912) are raw social documents, filled with a kind of Hogarthian anger. So was Bellows. A part-time anarchist and co-editor of a socialist periodical, the Ohio-born painter belonged to a generation of the American left swept away by Senator Joseph McCarthy.

So the National's show – just a dozen works in the Gallery's Room 1, of which four are by Bellows' fellow-'Canners – is variously surprising. The first is that it is there at all. If the Ashcan School was socially engaged, it was also driven by national bolshiness – a sense that American Impressionists such as John Singer Sargent were effete, Jamesian figures trying to pass themselves off as French. Not so Bellows: if his work Cliff Dwellers could talk, it would sound like Top Cat. Possibly as a result, European galleries tend to dismiss early 20th-century American painting as shaggy and parochial, which, in the case of Bellows, could hardly be further from the truth.

The bigger surprise, though, is that there is not a tenement to be seen in this show. It is often said that you can only understand the greatness of Picasso's painting if you know that he could draw like Ingres. The whole eyes-on-the-side-of-the-face thing was not the result of poor draughtsmanship. Equally, Bellows did not paint fire escapes because they were all that he knew, or even because he was poor, which he wasn't.

The first work in the National's show is called Three Rollers and is of Monhegan Island off the coast of Maine. The rollers of the title are not out at sea, but a trio of hillside terraces receding down to a beach. Bellows's roiling paint is laid on in big, wet strokes, a match (although the American probably wouldn't have liked the comparison) for Manet at his wildest. In The Big Dory, the elementalism of Monhegan becomes bound up with the power of men launching a fishing boat, the whole realised as a hyper-lit frieze which prefigures the murals of Diego Rivera. On the side of the boat is a shadow cast by Bellows' own easel, the fishermen's work and his own part of the same great force that is America.

If we have seen Bellows at all, then it is unlikely to have been like this. Perhaps the oddest work in this small, bright show is Blue Snow, The Battery, which resembles – intentionally, one assumes – a lithograph by that most American of duos, Messrs Currier & Ives. Although the scene seems to be of some upstate small town à la Washington Irving, The Battery is actually a park on the tip of Manhattan Island. As early as 1910, early skyscrapers would have edged in its landward side.

As with Excavation at Night, a glimpse into the foundations of what was on the way to being Penn Station, Bellows' interest is in excavating a pre-existing America, a place of primitive energy distilled in the working man. The link might, I suppose, have been more clearly spelled out: it would be easy to leave this show seeing Bellows as a regionalist painter, just as coming to Picasso via his early drawings might leave you thinking of him as a gifted traditionalist. Maybe the National should do another Ashcan show later. I'd certainly go.

To 30 May (020-7747 2885).

Next Week:

Charles Darwent strolls through Watteau: The Drawings at the RA

Art Choice

EO Hoppe's photographs capture inter-war Britain, and a host of famous faces from George VI to George Bernard Shaw. Study the British character at National Portrait Gallery, London (to 29 May). Or take a look at snapshots of the mean streets of 1970s New York – the Barbican Gallery exhibits Pioneers of the Downtown Scene (to 22 May).