HOW THE OTHER HALF LIVES

Tony Blair claims to be the `One Nation' Prime Minister behind whom `people from all walks of life, all classes, all parts of Britain can unite'. Who does he think he's kidding?

A couple of years ago, flicking through a book of aerial photographs, I began playing a silly game. The photographer had worked from such unusual angles and perspectives that, to my eye, certain bits of the landscape had the look of body parts. Intrigued, I started reconstructing Britain as a human figure, or body politic. Lulworth Cove, in Dorset, resembled an ear. Orford Ness, in Suffolk, and Spurn Head, where the River Humber enters the sea, provided a pair of arms. Silbury Hill looked like a nipple. Striding Edge, in the Lake District, served as a spine. Teeth came courtesy of the Needles, off the Isle of Wight. Numerous ancient burial sites competed for the role of navel.

So it went on. Keep the game up long enough, fitting all the pieces in place, and I knew I could end up with something like the Cerne Abbas giant, a figure of mythic potency, a sleeping giant, one body, one nation.

Since Labour's election landslide, the image of Britain as a unified body seems much less whimsical than it did when I assembled that collage. Throughout the years of Thatcher and Major, the political map of Britain looked divided, its top half poppy red, its bottom lavender blue. Not any more. One of the key moments of the campaign was Tony Blair's speech about Labour as the "One Nation" party, "behind which people from all walks of life, all classes, all parts of Britain can unite ... a Britain with shared values and purpose ... where no one is cast out." It's true that to win the hearts of "Middle England" (wherever that is) Blair had to change Labour's hue: there's a rinse of blue through the old red, making the colour purple. It's also true that the map of Britain still has mottled patches, not least those liberal bruises of yellow. Still, the dream of unity seems closer to reality now than it has done for many years.

Or does it? There remains an embarrassing obstacle to national oneness: the North-South divide.

No one is sure exactly where to locate this divide. Does it run in a line from the Humber to the Mersey, or from the Wash to Chester? Should Passport Control lie further down, closer to Birmingham, or even Watford Gap? Is the divide really a diagonal from the Exe to the Tees, separating the upland North-West from the lowland South-East? And how about Scotland: should it be included in the equation or - since they have their own North- South differences - is it best to think of this as an English, not a British, phenomenon?

The topography of the North-South divide is complex. But most people understand easily enough what's meant by it: not just that Northerners are different from Southerners, but that they're economically worse off.

FEW PEOPLE these days like to speak of the divide. Northern mayors, full of civic pride, are as reluctant to mention it as metropolitan powerbrokers. Least likely of all to acknowledge the divide are parties in government. On several occasions in the Eighties, Margaret Thatcher vigorously denied its existence. Kenneth Clarke said it was "a ridiculous simplification". Lord King, the chairman of British Airways, said it existed only in our minds, and that we should get rid of the complex. Most brazenly of all, Lord Young, in 1987, proclaimed that "until 70 years ago the North was always the richest part of the country," so it was only right and proper if "now some of [the wealth] is in the South. It's our turn, that's all."

Lord Young was historically inaccurate: even at the height of Mancunian prosperity in the 19th century, only a third of millionaires came from the North. Mrs Thatcher, too, was disingenuous: her Cabinet in the late Eighties had only one minister (out of 22) from the North - Cecil Parkinson. As for the business community, the fact that 90 of the top 100 companies in Britain at the end of the Eighties were based in London and the South- East gives the lie to the idea of an equal spread of wealth.

But politics and economics are only part of the picture. A 1993 Health Service Journal survey of SMRs (standardised mortality ratios) found that 13 per cent more people in the North-West die "unexpectedly" (that is, before the national average) - with poor diet, a higher incidence of heart disease and the underfunding of local health services key factors in the disparity. And a survey of population change in the decade up to 1991 found that whereas numbers in the South-East had risen, those in the North were down - a bottom-heavy redistribution, with the population of the Milton Keynes district growing by 42 per cent, while Liverpool's population fell by 8.2 per cent. Aptly, the zone which grew the most (both economically and geographically) in the Eighties, along the South Coast and up through the Home Counties, had the shape of the pounds sign.

But while the divide may have widened in the Eighties, it was created a long way further back. Historians of the phenomenon - including Graham Turner, David Smith, Frank Musgrove and Helen Jewell - emphasise its roots in the ancient past. Indeed, the more you read about it, the more it begins to seem a matter of landscape and human temperament than of mere economics. All in the head? No, it's as solid as Hadrian's Wall.

I GREW up on the Lancashire-Yorkshire border. The first divide I knew was a local one: on one side, the Yorkshire Dales - sheep, limestone outcrops, dry-stone walls; on the other, Lancashire and its cotton mills, a valley of industry. The divide was even audible in our voices: the local grammar school I went to had a catchment area of only a few miles, but we all spoke in slightly different accents, according to which county, town or village we came from.

So I never thought the North homogenous. But what united adults and children alike was a sense of belonging on one side of a much larger divide. Over the hills somewhere lay the Home Counties, Them; which made Us the away team, proud of where we lived but marginalised. Southerners don't have much of a sense of themselves as Southerners, unless they venture north. But Northerners are always deeply aware of being Northerners, wherever they are.

Growing up where I did, I resented the fact that the image which Southerners seemed to have of the North was uniformly urban: street after street of terraced back-to-backs - whether they be in Sheffield, or Manchester, or Liverpool, or Leeds, or Newcastle. From L S Lowry to Coronation Street, from Charles Dickens to Richard Hoggart, the story was the same: the North as poor, urban and - a few mill owners aside - exclusively working-class. Factories, foundries and fish-and-chip shops. In the gaps between the houses, slag heaps, cindery recreation fields and men in flat caps out walking whippets.

But of course my view of the South was no less of a cliche. The South meant London, the Big Smoke. Or if not London, a ridiculously posh and prettified village: thatched cottages, neat gardens, a church with its spire, a gentle river, unstrenuous hills, sunshine, a pub with the name of an English king, oaks and chestnuts, a cricket field, the vicar on his bicycle, mildness in the air, the elements tamed. Something a bit cutesy and picture-postcard-like. A place not so much lived in as passed through by tourists. A picture of middle-class affluence and affectation. There are villages in Yorkshire which don't look so different. Never mind. That was the stereotype.

WHEN did the divisive stereotypes begin? Most people would say in the 19th century, with industrialisation. In 1854, Elizabeth Gaskell published her novel North and South about a Southern family uprooted to a town called Milton-Northern (Manchester) in the country of Darkshire. The heroine Margaret's first impressions are ominous: a deep, lead-coloured cloud hanging over the horizon; long, straight, hopeless streets of small redbrick houses: "the ceaseless roar and mighty beat and dizzying whirl of machinery". For his part, John Thornton, the mill owner who pursues Margaret, has similarly sharp prejudices against the South - a society of ease and affluence, decadent and purposeless, a land of fops and idlers, "clogged with honey and unable to rise and fly".

Engels, Dickens, Ruskin - all added to the picture. Alexis de Tocqueville, another visitor to Manchester, wrote of the stream of industry flowing out through "this foul drain" to fertilise the world: "Here humanity attains its most complete development and its most brutish; here civilisation makes its miracles, and civilised man is turned almost back into a savage." In the era of carboniferous capitalism, of iron and steel, coal and cotton, canals and railways, it was the North which had the energy and the resources. Middlesbrough, on the Tees, was a single farmhouse in 1830; by 1880, it had a population of 50,000.

But the rift between North and South is much older than 100 or 150 years. Halifax, for instance, which in Dean Clough (built in the 1840s) once boasted the largest carpet factory in the world, has a wool industry that goes back to the 14th century. And the reports of Daniel Defoe and Celia Fiennes, two great travel writers visiting Halifax circa 1700, suggest that images of an incalcitrant and barbarous North predate industrialism by some way. As Macaulay put it, "No traveller ventured into that country without making his will. [The people] are scarcely less savage than the Indians of California."

A long line of English kings proved noticeably reluctant to visit the North. Only Richard III had any real feeling for the region - and no monarch has a worse reputation. Further back, there'd been the harrying of the north, by William the Conqueror, to punish the area for its Danish sympathies. Many people were killed, and villages destroyed. Northumbria, an economically disadvantaged area to start with, was ruthlessly laid waste. It was centuries before the region began to recover.

There's not much record of Northern counties in the Domesday book of 1086, itself a symptom of neglect. But we know this was a less populated region, one reputedly "lurking with wild beasts and robbers". We know also that a North-South division had already opened up before the 11th century between the kingdoms of Mercia and Northumbria. King Alfred refers to the divide, when he complains that very few men north of the Humber could translate a single letter from Latin into English. A sense is developing here of Northerners as truculent, or uncultured, or proudly independent, depending on where you're standing. The learning and influence of Bede, in 8th-century Northumbria, did little to dispel this impression.

Earlier, the Romans had divided their outpost of empire into Britannia Superior and Britannia Inferior, and never felt so secure in the North as in the more easily subdued South. Tacitus, describing Britain in the 1st century, compared the shape of the country to a double-headed axe, and reminded his Roman readers: "One must remember we are dealing with barbarians." Even the potter's wheel took longer to reach the North - the region lagging behind Southern fashions as usual.

You could say that whereas the South has been shaped by Roman and Norman influence, the North, because of Norse or Viking settlement, has a more Scandinavian character. There are people in Newcastle-upon-Tyne today who claim to feel more affinity with Sweden, Denmark and Norway than with London. (It's in the same provocative Northern-separatist spirit that the mill-owner's son in the classic comedy Hindle Wakes looks upon London as "the place where rich Lancashire men go for a spree if they have not time to go to Monte Carlo or Paris.")

Meanwhile, such were the tensions between Northerners and Southerners at Oxford University in 1252 that 12 peace-makers were appointed from each side. Even the Church of England is still divided into two provinces, one in Canterbury, one in York, and has been since the 8th century.

WHAT all this suggests is that the great divide is as old as the hills. Literally. Lack of hills in the South-East meant the region was best suited to arable farming; an abundance of hills in the North-West meant pastoral farming and, later, industry. In the Lake District can be found the oldest rocks in England: they're hard and ancient, pre-Cambrian, some 4,000 million years old, and naturally attractive, in their Alpine grandeur, to Romantic poets. The chalk downs of the South-East are younger and softer.

Rocks and hills affect human temperament as well as human activity. "Our soul is, above half of it, earth and stone in its affections and distempers," said the 17th-century philosopher Jeremy Taylor. Since the Pennines are often called "the backbone of England" it's no wonder if those who live close to them like to think of themselves as gritty and tough, and look down on Southerners as soft-bellied, spineless and effete - the lounge lizards of the Home Counties.

These myths may be simplistic but that doesn't make them any less pervasive. You can point out to a Northerner that vast tracts of the South - Cornwall and Devon, East Anglia and the Fens - are physically, morally and economically remote from the charmed circle of the M25. You can point out to a Southerner that now industrialisation is over, the North has cleaned up its act and become rather chic, its mills and factories turning into heritage centres, restaurants and art galleries. But the old ideas are too deep-rooted to disappear overnight. There are still Northerners who believe (as Eddie Waring pretended to) that Southerners eat with their gloves on, and Southerners who share the feelings of Beau Brummell in the late-18th century who, on being told that his regiment was being sent from Brighton to Manchester, said he hadn't bargained on foreign service when he joined up. On both sides there's a feeling of: sod the other half. Why not saw the country in two, so London can join up with Brussels while Manchester, Newcastle, etc, are towed out into the North Sea.

TWO DEVELOPMENTS are healing this rift. One is travel: better rail, road and air links have done much to break down prejudices and soften accents. The other is homogenisation. You can go to any medium-sized town anywhere in the country now and find much the same: the pedestrianised high street, the out-of-town shopping or leisure centre, the light-industrial estate with corrugated sheds. This is where most of us live now, in a place vaguely resembling Milton Keynes.

There are advantages in this. Few of us like to think of ours as a divided nation. And the erosion of difference feels decent and democratic. Rootsiness, after all, is a deeply Old Labour idea, the ticket on which Neil Kinnock fought the 1992 election when he lost to the Man from Nowhere, or Huntingdon, John Major. How much cooler to talk about where we're going than where we came from. Most of us are exiles after all, living away from the place we grew up, our feet in one place, our heart in another. It's a common condition of late-20th-century life, not something to bleat on about. We're all Europeans now.

Yet homogenisation has been predicted since Orwell and J B Priestley in the Thirties without ever conclusively arriving. And meanwhile there are cracks in the socio-economic fabric that can and should be closed up. New Labour has work to do here, and I'd like to think that Tony Blair, the first Northern PM since Harold Wilson, will tackle the problem rather than argue, as Mrs Thatcher did, that the divide is "all in the head". For a long period, we've lived like Disraeli's two nations, "ignorant of each other's thoughts and feelings". Now it's time to heal the rift.

But there are also other divisions we can celebrate. Flying over the country last year, by plane and helicopter, it struck me how rich and varied the English landscape still looks. However flattened out from 4,000 feet, and however genial when bathed in summer sunlight, sharp differences kept poking up. The human differences they give rise to, in how we talk and even feel, are ones that will never disappear. A good thing, too. They're the differences we're richer for.

! Blake Morrison's film `The Great Divide' will be broadcast on BBC2 at 5.50pm today.