Drawn together at last

Wyndham Lewis is one of our greatest artists, so why is his long-awaited retrospective taking place in Spain rather than Britain? Tom Lubbock reports from Madrid

If Wyndham Lewis had died in the trenches, he would have survived as Britain's great modernist. He was the gang-leader of Vorticism, the London avant-garde.

He's among the first generation of Europe's non-representational painters. In the approach to the Great War, he made a group of explosive, angular, syncopated abstractions that have an energy and subtlety equalling any of his contemporaries.

We would still be looking forward to what might have followed. What could he have become? Our Léger? Our Malevich? But he wasn't killed. And what actually followed was so diverse, so eccentric, so uneven – or should that be simply so original? – it has proved hard to find Lewis a place in the canon. Or rather, it's become a vicious circle. Lewis's oeuvre is never shown in sufficient mass to allow a proper picture to emerge.

He's not unheard of. There are shows from time to time. The National Portrait Gallery had an exhibition of his portraits just over a year ago. But there's never been the kind of show that might present him as a modern master. The Tate has several Lewises in its collection, brings them out occasionally. It's doing an exhibition of the Vorticist group next year. But as for a career survey, the Tate has given memorable retrospectives to Stanley Spencer, Paul Nash, Gwen John, David Bomberg. At the moment it's banging the drum, yet again, for Henry Moore. It almost did a general Lewis show to accompany the NPG's. It decided not to. Lewis always seems to miss his chance.

But now he's had a stroke of luck. I never expected to see it, but now Wyndham Lewis: 1882-1957 has opened; and of all places, in Madrid. At the Fundació*Juan March, until the middle of May, you can see the retrospective that Britain has never managed to get together. Why Madrid? Lewis spent some months there as a young man, but the present reasons are fluky. The Juan March Foundation is a vastly endowed private cultural institution, roughly a Spanish Guggenheim, for which there is no British equivalent. It has a curator who took a fancy to Lewis. So, they're having a show, which offers to break "the thundering silence".

And it is the show. A few serious omissions, but this is about as complete a collection of Lewis's paintings and drawings anyone could hope for. They're shown alongside his numerous books and pamphlets, and the briefest glimpse of the man on film. The display is beautifully perspicuous. The exhibition doesn't tour.

Is it the show that will finally make his name? Lewis's visual talents were sporadic. Some of them, no one denies. There are those abstracts. His line drawing, especially in the life studies from the early Twenties, has an exact curvature, an inventive construction, matched only by Picasso. There are the defining portraits of his literary contemporaries, Ezra Pound and T S Eliot and James Joyce; there's the magnificently farcical Mr Wyndham Lewis as a Tyro, a phallic grinning head all made of cutting edges. And then there are Lewis's colours, incredibly intense, surprising, delightful. Where else do you find such yellows, such pinks?

So now: why not London? After that build-up, it sounds a purely rhetorical question. But it could also be a real question. There may be critical reasons why Lewis as a whole will stay a minority taste. He is certainly an offensive figure, both personally and politically. He was rude to almost everyone. In the early Thirties he came out for Hitler (and didn't retract till war started). These things harmed his reputation. But in his art, too, where he is seldom offensive, Lewis is an awkward customer. There are outbursts of disparate brilliance. But the case against says: too many strings, too tangled up.

Lewis's essential apercu was that Cubism could have content: it's deconstructed bodies and dissolving spaces could be taken, not as a formal language, but as a strangely living world. It proves a very versatile idea, perhaps too versatile. Lewis turns it all ways.

He creates outlandish, comic characters: look at the bright red, knife-sharp features of the Tyros. He performs like a satirical cartoonist, sometimes social, sometimes political, outlining 20th-century types – fascists, sportsmen, starlets – with masterful graphic formulae. (It's relevant to recall that H M Bateman and Low were both contemporaries). There are scenes from modern life or history or anthropology. Or we're in a realm of imagination, myth-beasts, machine-men, futuristic and after-life regions. All these possibilities coexist with an impulse for sheer pattern, at first sharply geometric, later fluidly calligraphic.

Nothing is straightforward. These various tendencies overlap and obscure themselves. The narrative paintings of the Thirties are especially unplaceable. The queue of forms in One of the Stations of the Dead: is it the underworld, or the Underground? The immersed swimmers in The Tank in the Clinic: is this fashionable therapy, or a stage of Purgatory? The doll-like fragmented nudes in Beach Babies: sunbathers, or ritual figures?

He's a fascinating but frustrating maker. There's nothing like these images anywhere else, but they never quite work. It should be a strength, the way Lewis mixes a modernist idiom with all these "low" genres – caricature, cartoon, illustration, fantasy. But his paintings can't resolve their mixtures. They switch from one mode to another on the same canvas, add some irrelevancies, and disintegrate. Apart from the portraits, there probably isn't a totally achieved painting after 1921.

That's a problem in a comprehensive retrospective, which also suggests a reason: all those writings sitting in glass cases. Lewis chops and changes, from fiction to polemic to theory to art. He has the curse of the multi-talented and permanently broke. He paints in spurts, and has to keep refinding his hand, and after a bit he can't.

The drawings are another story. Here the expectations aren't so "high", and the practice is more continuous. If you made a retrospective just of his pen, pencil and watercolour works, you'd have a running sequence of astonishment. You'd keep a lot of abstracts and portraits, and you'd enter a world where the mix-ups fuse. Here you meet the Lewis hybrid quasi-human – robot, puppet, spirit, design – flying, buried, standing in formal rows. The quickness of their making gives life to these creatures. They achieve the satirical-mythical synthesis that the oil paintings struggle for.

Drawing helps in other ways. Lewis is seldom happy having to fill a whole picture, taking the image right out to the edges. In drawings he doesn't have to. He works out from the centre, stops where he wants. He invented a new form of drawing where a contained image becomes a creature or a little world in its own right. In Archimedes Reconnoitering the Fleet, the scene floats on the page like a spaceship. And this is not the only place where Lewis can seem to be simply one of the great doodlers.

Drawing frees his art. It makes it lighter, more equivocal, more open to his and our imagination. In any oeuvre, we tend to give priority to the paintings, and treat the drawings as studies, footnotes, juniors. Now we can see a full Lewis retrospective, it seems that with his art we should reverse those values. He's one of the English graphic masters. He's not quite as "great" an artist as some of us might have wished – but a rarer one.

In the 1940s, as he lost his sight to a brain tumour, the drawings (small as they are) become ever more metamorphic, visionary, cosmic. Seas, embryos, worlds, thoughts, concatenations of forms that are impossible to grasp ... His last image, Red Figures Carrying Babies and Visiting Graves (1951), is another queue-cum-frieze, shimmering uprights, set in this life or another. It's like William Blake of course, and not much else, before or since.

Wyndham Lewis: 1882-1957 at Fundación Juan March, Calle de Castelló, Madrid (0034 91 435 4240; March.es) to 16 May