ART / That was the decade that wasn't: 'The Sixties' is back again in all its brashness at the Barbican

IT OUGHT to be possible to put on a beautiful and moving display of the best British art of three decades ago. 'The Sixties', at the Barbican Art Gallery, is not such an exhibition. Round every corner of its confusing installation one finds work that is shallow, foolish or merely trendy - just the sort of thing that in those days gave art a new kind of bad name.

Personally I enjoyed this aspect of the show, mainly out of nostalgia for the bumptiousness of it all, also because one must be indulgent to youth (especially if it is your own). It is not the inadequate artists who disappoint so much as the ones we know to be good. Sir Anthony Caro is still the great artist of the Sixties and the decisive work of other sculptors associated with St Martin's - Barry Flanagan, Phillip King, Tim Scott and William Tucker - is more achieved than anything else in three dimensions. Bernard Cohen, John Hoyland, Bridget Riley and Richard Smith are still the superior painters of the period. But they could all be better represented. Surely we want such people at their very best?

Alas, the show is negligent of the real achievements of the Sixties. It was devised by Dr David Mellor of Sussex University, both as an exhibition and a book. In the book (Phaidon, pounds 22.95), Mellor states his purposes and declares some limits. He will not include any older artists, certainly not Henry Moore, Victor Pasmore or Francis Bacon; nor any of the abstract painters connected with St Ives, even such metropolitan people as Patrick Heron and Terry Frost; in fact he won't have anyone who worked outside London. Within London he won't have any of the figurative artists known as 'The School of London'; and finally he won't have any constructivists.

So while the show looks open to anything when you wander about, it is also determined by omissions. The artists who are included fall under the themes of Mellor's chapter titles, also the titles within the installation: 'Action', 'Dissent', 'New London', 'Places', 'Packages', 'Bodies and Gender - heroines and heroes', 'Light Fantastic', and 'Spaces Beyond'. These categories include advertising matter, photographs, film stills and magazines as well as paintings and sculpture. For Mellor's thesis is that there were two opposing yet complementary trends within the decade: two avant-gardes, 'one culminating with 'Situation' and St Martin's in the early Sixties, the other focused around an 'Underground' tradition of action, dissent, performance and the deployment of new technical resources'.

University lecturers should not write 'focused around' but I see what Mellor means. For the tradition of underground dissent is patchy, grungy, never explicit except in expressing its dislikes, dark, messy and inchoate. This is unlike Mellor's better prose. His expositions dart from subject to subject, never lingering, often making fresh and enlivening parallels, even though he never considers works of art for their own merits. And underneath this writing there slowly laps and eddies a bituminous runnel of discontent, from William Green's black painting to Stuart Brisley's black and brown painting, from John Latham's banality of mutilated books to Gustav Metzger's 'auto-destructive-art' and finally to the cartoons of Steadman and Scarfe, now revealed as less interesting than the establishment cartoonists they are supposed to have challenged.

Within this strain, Denis Bowen's little picture has remarkable verve. I was also surprised by Peter Hobbs's North of Metaphysics, an abstract picture apparently influenced by Rothko and Barnett Newman. This was one of a number of his works photographed on bomb sites by Don McCullin. Gillian Ayres's Cumuli, probably the best of all British tachiste paintings, points towards her later colouring. But Cumuli is of 1959, and none of Ayres's Sixties paintings is in the exhibition. There is compensation for this absence in a startling painting by Ralph Rumney and especially in a beautiful abstract composition by Henry Mundy, a sensitive painting in a show that does not count sensitivity among the first of virtues.

Brashness, rather, is seen as the clue to 1960s painting and the loose group around the Situation exhibitions in the first years of the decade. Robyn Denny's contribution is emphasised. Indeed he is a presiding spirit of the exhibition, since he provides both its first and final paintings. Two tall canvases by John Plumb are worth seeking out and it is good to be reminded of the open and heraldic designs produced by Gordon House in those years. Of the Situation painters, Bernard Cohen was surely the most inventive. I doubt however whether his best painting was done at the beginning of the Sixties rather than later. The same could be said of Richard Smith.

David Mellor has over-emphasised abstract painting in the late Fifties and early Sixties because he believes that this kind of art was swept away by Pop. I think this is wrong. Practically all the abstract painters got better as the decade progressed, while the pop artists all got worse. It's diverting to see paintings by David Hockney, Derek Boshier, Peter Blake and Allen Jones, but their art doesn't stand up to a long look. Nor does that of Pauline Boty, whom Mellor regards as a significant figure and who is given a lot of space. In truth she was a derivative painter. Boty's lively presence on the London art scene is one thing: the quality of her work is quite another.

Boty's short career does however emphasise one terrific feature of Sixties art life. Suddenly, anyone at all could have a go. The art world had never been so open (nor has it since). Hence the working-class and provincial contributions to the spirit of novelty and adventure. At St Martin's, the most exciting centre of Sixties art, the sculpture department took on people who walked in from the street. Mellor has done well to find a 1961 sculpture by Maurice Agis, made I think when he was a student there, and he is right to notice that there was a utopianism in Agis's later environmental art.

Idealism was in the air, just as important as satire and dissent, though harder to define. I think the mid-Sixties was the last time when abstract art was the natural companion of social optimism. The light, clear and highly defined abstraction of the period often proclaimed that it had no purpose beyond its own aesthetic life. Yet it now seems to me that such painting and sculpture did envisage a place within an improving world. If the world's improvements included worldly things, well and good. Nobody wants a utopia in which you can't indulge in a bit of consumerism, go to the movies or dance to the Beatles.

So Robyn Denny's first significant work of the new era was a mural for Austin Reed, a shop that wanted to update its image. And of course consumerism came to include art itself. The galleries expanded, became younger, were fashionable and sold work as quickly as possible. Puritans thought this was wrong, but from the vantage point of a recession it does seem part of a golden age. Gold, incidentally, is one of the colours of this exhibition, in all its pin- ups, in a nice painting by Peter Blake called Gold Leaf (after the cigarettes) and in David Hockney's hair-do. Another Sixties colour is pink: blossomy, cheeky, artificial or ethereal. Thus the hues of wealth and fun express something special about the times.

The best pink work is Phillip King's cone sculpture called Rosebud. This was also one of the first pieces to be made from fibreglass, a material the artist had spied in shopfitting showrooms. On the whole the sculpture in this exhibition looks better than the painting, despite the fact that it has to fight for its space. David Annesley's Swing Low is a particularly fine invention. The two Caro sculptures are rarely seen and deserve prolonged thought, for they have the best Sixties combination of radicalism and light-heartedness, and are also elusive. I mean that you can't get a grip on their physical nature. Like so many of his friends, Caro was inspired by the mood of the times. And what was that elusive mood, so hard to recapture today? Happiness.

Barbican, EC2 (071-638 8891), to 13 June.