Escape artists: A new exhibition of English pastoralism is a poor harvest

Graham Ovenden (born 1943) Poplars, 1991 (Courtesy of a private collection.)

In 1915, the poet Edward Thomas had enlisted, and somebody asked him what he was fighting for. He bent down and picked up a pinch of earth from the ground, letting it crumble between finger and thumb: "Literally, for this."

It sounds like a parody of patriotism. He doesn't cast a sweeping hand over the contours of the beloved landscape. He stresses the extremity of his feeling for England's land by fixing it on to a mere soil sample. Not any ideal, not any beauty, the sheer matter of this earth is what he will die for (as two years later he did). But in the conceptual distance between that smidgen of dirt, and the enormous meaning attached to it, Thomas's gesture seems like a piece of contemporary art.

It is very hard, though, to imagine an actual piece of contemporary art that would carry this sort of sentiment. In general, contemporary art and the countryside are chalk and cheese. Contemporary art believes in the city. The city is modern, progressive, secular, cosmopolitan, fragmented, conflicted, while the country is nostalgic, conservative, spiritual, national, unified, pacified – all wrong and boring. And the city, of course, is where art is made and shown and sold and talked about.

Conversely (and I don't think I'm alone), when I'm in the countryside I find it difficult to fix my attention at all on contemporary art. When I'm in London, for better or worse, it occupies my mind quite a lot. When I'm among the hills and trees and wind it seems like a bit of remote metropolitan gossip, roughly on the level of the congestion charge. I do think about some art in the countryside: Poussin's landscapes, for example, and Paul Nash; seldom anything more recent.

Yet, since I believe art should be universal, and there shouldn't be a great field of experience on which it is simply blank, and since I observe that, in their lives, contemporary-arty people are by no means indifferent to the draw of the countryside – well, I conclude that the countryside of the present is a kind of artistic blind-spot, a challenge waiting to be met. Somewhere along the line it got lost.

Ancient Landscapes – Pastoral Visions: Samuel Palmer to the Ruralists is an exhibition at Southampton City Art Gallery about the art of the English countryside. It tells a story, which looks to me like the story of something going wrong. But that isn't how the show sees it, and it wouldn't be so useful if it did. The story is, at any rate, a true history. It isolates a particular line of succession in English landscape. It bypasses the big, blustery, gassy views of Constable and Turner, to focus on the more small-scale, mystical, land-centred tradition. What's useful is that it comes up to date.

It begins in the 1820s with the first English avant-garde, the Ancients, Samuel Palmer and his friends, making their visionary home in Shoreham, Kent. It picks up, after a big jump, with the rustic English Modernism of the 1920s to 1940s – Paul Nash, Graham Sutherland, John Craxton, John Minton, Eric Ravilious. It ends with that curious 1970s art manifestation, the Brotherhood of Ruralists.

The show constantly intercuts between these three chapters, and particularly (since it doesn't have much of the Ancients to show) between the works of the Modernists and the Ruralists: the idea is to make continuities more apparent than differences. And it gives special prominence – as if he were the continuing standard-bearer of the line – to the recent work of one former Ruralist, Graham Ovenden.

If things had been shown in sequence it would have been clearer – and it is clear enough, anyway – that this tradition has become, as it's gone on, increasingly desperate. But it might be truer, and actually more encouraging, to put it another way. The tradition was desperate from the start. It went wrong when it forgot this, and decided it was about making things nice.

That well-known desperado William Blake was its true originator. His 17 woodcut illustrations to a translation of Virgil's pastoral poems are among the smallest and most influential works of English art. Some are in the show. Each is a strip about the size of big postage stamp, a tiny glimpse of an alternative world beyond.

Palmer responded vividly: "They are visions of little dells, and nooks, and corners of paradise... There is in all such a mystic, a dreamy glimmer as penetrates and kindles the innermost soul, and gives complete and unreserved delight, unlike the gaudy daylight of the world."

Blake's woodcuts are certainly dark, though not all are nocturnes, and their tightly confined miniaturism makes them feel like enclosed little worlds. Those qualities Palmer forged into his own womb-like icons of the English village. Dark even when it's day, the land lies snugly between a framing arch of trees. Hills hump up, clouds close in, sleeping sheep and fields of sheaves are safely tucked together.

Unlike Blake, Palmer was a militant Tory, anti-industrial, anti-democratic. His vision is powerfully defensive. Everything is enfolded, cradled, oystered, with a bright central moon or a glimmering spire as the ruling heart of the cluster. It's a world that holds us: a close, stable and integrated cosmos of nature, sky, agriculture, worship.

But when Palmer's example was taken up by artists between the wars, it wasn't just as a conservative alternative to Continental modernism. Palmer could only catch on because – with his simple shapes and tight design – he already looked like modern art. Some imitators used this idiom to create a nostalgic embracing nookiness. Others found weirdness in it, and anxiety.

I'm sorry that Sutherland is such a weak and cautious painter. His ideas are good. Those half abstracted hieroglyphs of natural forms – compounding knots, nests, roots, spikes, holes – promise a "green" Francis Bacon, but they never deliver.

Nash is made of stronger, stranger stuff. He has a taste for megaliths and long barrows and blasted trunks, but they don't appear with the impact you might expect, as calmly ancient and spiritual symbols – rather, as odd and inexplicable forms that have arrived out of nowhere. His sense of landscape never recovered from the Western Front. It's both numinous and tortured.

But the Brotherhood of Ruralists was a wilfully retro and escapist movement. Elsewhere in the British art world the first wave of conceptualism was at its height. (Richard Long did nature by making carefully plotted geometrical walks.) This group of seven painters, with Peter Blake at their head, were off to the land of faerie.

True, only by narrow art world standards could that seem an utterly untimely development. There were plenty of hippie-minded people around in the mid-1970s with similar tendencies, and these artists certainly struck a chord: an entire edition of the Arden Shakespeare had cover illustrations commissioned from the Ruralists.

Like the hippies, though, they never had much sense of what they were up against. They thought it was enough to say "let's pretend", but they didn't see that their imagination of mystical, deep, England had already been fully colonised by commercial imagery. Their pristine visions of an unfallen world came straight from a pretty advert for soap or air-freshener.

They had their moments. There's always been a bit of neo-surreal hauntedness in David Inshaw's work, with its hard, long shadows falling across flat grass. But for the curator of the show to make Ovenden the living hero of the story can only be evidence of close personal friendship. If I really wanted to put someone off the English countryside I'd do it with Ovendens and their emetic combination of lurid colour, featureless smoothness and air-brushed soft-focus.

The point of the countryside is not to be an escape route, but a line of resistance. Life in the modern world, with all its benefits, has always carried a feeling that things have gone horribly wrong. The countryside, with its remnants of unmodernity, is one way of strengthening that necessary feeling.

Art that does this properly will, of course, show signs of struggle. It won't have the slick serenity of the Ruralists – nor indeed the pixie craftsmanship of Andy Goldsworthy. Its pastoral visions will have a bunker mentality like Palmer, or a battlefield mentality like Nash. And I dare say there's some decent art still to be made on this ground.

Ancient Landscapes – Pastoral Visions: Samuel Palmer to the Ruralists, Southampton City Art Gallery (023-8083 2153), to 22 June; touring to Victoria Art Gallery, Bath (01225 477233) in July, and Falmouth Art Gallery (01326 313863) in September