They call him the Mannie, and panting, almost out of breathe, I can see him rising over the dying bracken and the dry gorse at the top of the hill — a sandstone giant, atop a 100-foot column of colonial splendour. This is the first Duke of Sutherland, and tiny beneath his plinth, here since 1836, I can see where Scottish nationalists have been digging to topple him.

The Victorians called him the Great Improver. The towering Duke was English, of course, and everything you can see from this peak, from the humped mountains in the distance, to where the coast disappears out of sight, he inherited with his Scottish marriage. This was, and much of it still is, the Sutherland Estate, the barren result of the Duke’s improvements — the Highland Clearances. Deer skip and chew through lichen and tufts, where his men burnt whole villages, as the hill tumbles into the sea.

Poking out of firs, as vulgar as Neuschwanstein, is Dunrobin Castle, to this day the seat of the laird. Not only this view, but the Highlands as we know it, is still a patchwork quilt of enormous estates created out of the Clearances. Today half of the privately owned Scottish countryside still belongs to 432 landowners. Nationalists call this a colonial creation, and radicals inside the Scottish National Party are pushing Holyrood to begin dividing them up.

Hunger for land reform has grown in the Highlands alongside nationalism. The attacks on the Mannie began in the Nineties. At first, there was a plot to dynamite it. Then, in green paint, they daubed “Monster” all over him. SNP politicians in Inverness began hectoring for the Duke to be ripped down and replaced with a Celtic cross. Nationalist intellectuals suggested breaking his column, and then smashing him limb by limb, to lie ruined like the torched crofts of his 15,000 evictees.

Twice, men with tools have snuck up at night, ripping out sandstone corners of his plinth, digging under to topple him headfirst off the ridge. They haven’t stopped. A plot to deface him is now afoot. The closer Scotland gets to independence, the closer the Mannie, and the estate system he symbolises, is to a full-frontal attack.

The road north from the Mannie, winding past the coves and villages established by the Duke for his expellees, is one of the best places to think about what is happening in Scotland. What were the Highland Clearances and why do they matter? The barren moors as we see them today are a modern, man-made wilderness. After the Jacobite rebellions, Scotland’s feudal lairds, who once saw themselves as clan chiefs, protecting upland villages, evolved into 19th-century British lords. Their inheritance was overpopulated, unprofitable and blighted by disease. To turn a profit, men like the Duke of Sutherland believed they knew the answer. They would empty the hills, forcibly resettling their tenants. Sheep, and profits, would replace them. Eviction would be swift and villages would be set alight if they resisted. Those who could not be resettled on the coast would be sent to the colonies. Two centuries on, the sheep have gone. The bracken and the heather are now grouse moors and deer forests, filled with the childhood memories of the aristocracy.

As late as the 1970s, there was a British story here in most people’s heads. It went like this: in 1707 a poor Scotland and a rich England fused. The results were fantastic. Families rushed to work in the spectacularly industrialising Lowlands, and destitute crofters set out to conquer and colonise the world under the Union Jack. The Highlands, went the old reading, had been improved from misery into thriving sheep farms and grouse moors, with the people packed off to new, better lives in Canada and the other thriving white colonies. But ever since the 1970s, another story has come to fill the minds of the majority in Scotland.

In 1973, a radical theatre group toured the Highlands. They were performing a play by John McGrath, The Cheviot, The Stag and the Black, Black Oil. The church halls were packed. The Highlands, the story went, had not seen any improvements. In fact, it had been a colonial frontier. Treacherous lairds, conniving with London money, had expelled their own people from the lands. Then they ruthlessly exploited them: first the stolen moors had become sporting estates, and then came the fire-belching oil-platforms of the North Sea. Actors screamed, chased by the Duke of Sutherland’s men across the stage, until an actress sung auld Gaelic melodies of woe. It was an instant sensation; as it toured the Highlands, villagers were in a state of shock. Never before had they seen the laird insulted, ridiculed or condemned. The actors put two demands in people’s head: it’s Scotland’s oil, and it’s Scotland’s land.

In 1974, a radical, little-known theorist published a book. The Break-Up Of Britain by Tom Nairn was sniggered at in London as fantasy. It is now seen as a milestone in Scottish writing. Nairn argued that Britain was nothing less than an old, aristocratic imperial state: a decrepit thing holding back democracy like Austria-Hungary. Seen from London, this seemed faintly ridiculous, but to a new generation in Glasgow and Edinburgh it felt bang on. Nairn’s villains were the men who owned the Scottish countryside. Not only were the Duke of Sutherland’s heirs sitting Tory MPs, they stuffed the House of Lords, amending any bill that touched their estates. Scottish nationalism, said Nairn, who would inevitably address the SNP conference, was nothing less than a revolution against the aristocracy.

Along the coast road, a few miles north of the Mannie, I find that a new history is being erected in Scotland. Here is the village of Helmsdale, all shuttered shops and pubs, where Alex Salmond came in 2007 soon after becoming Scotland’s First Minister. At dusk, bluish lights from oilrigs blink from the sea as I stand by the SNP’s anti-monument: The Emigrants. This is dedicated to those driven out of the hills by the Duke of Sutherland. A bronze couple and their children, evicted to lives overseas, the father looking forward, the mother looking back into these tumbling hills of pleasure shooting, with hate. The book, the play and the statue all tie together — into the emergence of a new popular mythology, replacing at its heart Britishness with the Clearances. It is Scotland reimagined as a second Ireland, England’s victim, not England’s partner. Everywhere I go in the Highlands, I find this past triumphant in people’s heads, one that views the sporting estates as historically illegitimate. And rising with this new past is a new demand for “our land”.

When they free Scotland, SNP activists dream they’ll free the hills. In Highland pubs, I find the land reform dreamers. Cleaners are planning to turn the grouse moors into national parks. Water-maintenance technicians are sketching out how to turn the gamekeepers into park rangers. On the road to Inverness, in one hamlet after another, is a militant SNP.

This is a simmering revolution. Land reform was not a topic discussed in Scotland’s polite society before devolution. Raising the issue of the most concentrated land ownership in Western Europe was met with looks of scorn at conferences and seen as an attack on private property. Today it is a constant refrain; the referendum campaign has got people thinking not only if they want Scotland to be independent, but what kind of Scotland they want to live in. Long-bottled frustrations have released something emotional and a little utopian.

In the Highlands, I find dreamers everywhere, even in Aviemore. There has never been much politics here, 130 miles north from Edinburgh. Or at least not outside the ballrooms and billiard rooms of the Georgian manors. But something quite remarkable is now happening in this town with a big Tesco and less than 3,000 people: tenant farmers and boiler repairmen are talking about history.

Before the referendum, a couple of crusty old folk would meet as the SNP, but since then the party in the area has swelled from 60 to more than 260. This is happening everywhere. There were 25,000 members before the vote; there are 115,000 now. This momentum, and the SNP’s sweep of 56 out of 59 seats in last May’s general election, is why two-thirds of Scots now think independence is inevitable.

In Aviemore, the SNP is now an evangelical little world: a book club and a supper club, with its fundraisers and fêtes, trips to the party conference and walks around the loch. This has filled the town’s void of association and faith. Protestantism no longer means what it once did; kirk attendance has been in decline for generations. The Highland Regiments, their prestige smeared, are not the mass recruiters they once were. All the icons are tarnished; the Royal Family has been ridiculed for decades by the Scottish press, any pride in the imperial past is felt to be impossible, akin to pride in racism.

It makes this social knitting together so precious to those in the SNP that they wave away any critique of its policy or politicians. At the lounge bar opposite the railway station, I sit and eat sandwiches with some of the local branch: a Christmas tree salesman, an electrician and an office manager, who is a single mother. How they love their party. “I was never reading before,” says the Christmas tree salesman, “And now I am. I’m watching Question Time.” As they talk, quite breathlessly, I realise how this sudden, much-longed-for movement is not something the SNP really controls. It matters what three random people think in Aviemore, because these new members can overrun the party machine. “We’re a democratic party,” says the office manager. “And if we don’t like it, we’ll push Nicola to go tougher.”

The SNP has become, in this small country of 5.3 million people, something enormous: more than one in 50 people in Scotland are members, a rate akin to that of a one-party state. So quickly has it grown so huge, it is unclear how this giant will now walk. Will these 95,000 new members, the vast majority of them leftists, overwhelm the party’s centrist financial instincts? Or will the SNP turn into another grand institution where they scarcely matter at all? Land reform will be a litmus test. The more the movement reshapes the SNP, the more radical what happens on the hills will be.

“The estate system does not belong in the new Scotland,” says the electrician. “We want the land used for the common good.” It is a clue from the future that at their first conference as a swollen party a Land Reform Bill presented by Nicola Sturgeon was rejected. The proposed legislation was intended not only to force sporting estates to pay business rates but to strengthen tenants’ rights, install a permanent land commission and give Holyrood the power to force sales to certain community buyouts.

Party radicals now want land reform to go further: not only to make community buyouts impossible to resist, but to ban landowners leaving their estates to a single heir, breaking them up over time. They want punitive taxes to force sales. They may not couch it in these terms but they want Scotland to follow Ireland, where before independence more than half the country was owned mostly by absentees in estates of 3,000 acres or more. A meat-mincer called land reform has all but eliminated them.

To nationalist activists, this is a tempting crusade. With Scottish independence off the agenda for the next few years, and these little platoons hungry for the ruling party to set about doing radical, transformative stuff, the grouse moors and deer forests are sitting targets. The new campaign, “Our Land”, is growing in popularity.

“We now run Scotland and we will manage this land a different way.”

But you cannot talk land reform without talking history.

“That happened after the dark . . .”

I’m sorry, what?

“Oh, I meant the Act of Union.”

Without prompting, the SNP activists begin talking constitutional history. I am told how the Statute of Westminster in 1931 returned sovereignty to colonial subjects like Canada and Australia and should have been applied to Scotland. I am told that the United Kingdom is the remains of the British Empire and must be broken up to be fully democratised, above all to crush the landowners’ club that is the House of Lords. Again and again, the Clearances are alluded to.

“You know what,” says the Christmas tree salesman. “I know these hills, I know them, these bare places, and when you drive around there’s nothing. Miles and miles of nothing. And when I went to England, it’s like this, bam, bam — village after village after village.” He pauses, and catches his breath.

“When I’m up the hill, I can see it now — there’s a ruined croft, there’s another ruined croft, there’s the rubble of a village, there’s another. And that’s when I got it. That before the Clearances, we were not a wilderness, we were full of villages like England up here. I’m dreaming, really, that in the land reform it should say every little shieling [tiny hamlet] should be repopulated, with futuristic little villages with solar panels.”

There is drizzle on the windscreen as we drive into the Cairngorms. My guide is an activist from the SNP, whom I’ll call Alex. “Don’t quote my real name, or put my job,” he pleads. “When you live in the country lots of your work depends on these lairds. It’s not just me, but the builders, the joiners, the electricians and gamekeepers. They’re all SNP. They all want land reform. But they keep it quiet. You can’t fall out with the laird — that’s your job gone.”

Alex keeps talking as the road turns into Forestry Commission firs, miles of identical green clones. He pulls up, crunching over gravel at a cow-gate. His hair is thinning, his eyes are blue, and at the nadir of his career he managed a local authority team of lawn mowers. Above all, he hates Tony Blair and thanks the SNP for turning him into someone who reads books.

“When you’re a working-class Scot,” he sighs, “you always get this feeling when you go into the land. That you don’t belong there. That it’s not yours. Oh, I can’t go here. I can’t go there. I shouldn’t be fishing here. I shouldn’t be walking there. Maybe I should hurry up and leave now. Maybe I’m disturbing him. Maybe the laird’s guys are coming and they’re going to shout at me.”

We drive on, into the glens. But we are 40 years too late for the countryside. The villages are gone. One, after another, in whitewash, all shuttered up. “That’s a holiday home, that’s a holiday home, that’s a holiday home, that’s stayed in, that’s a holiday home, that’s just been sold to be a holiday home.” The acquirers, for the most part, are English.

The lane curls and curls, but this is not the Highlands that used to be printed on the biscuit tins. There are still farms, but they are light-industrial zones, and ever more of them are manned through the harvest by seasonal Romanians and Poles. As we pick up speed, I begin to notice things: how the blackberries grandmothers used to pick for cakes, and the sloes, are rotting on the bushes.

“We can’t afford to live here any more, all these holiday homes have pushed the prices up to like half a million pounds for one of these cottages and they’ve killed ’em off, all the shops.”

This means the Highlands look open, immense, but actually for the people here the little slivers where they really live are cramped and narrow. You can’t build here, that’s an estate. You can’t build there, that belongs to the laird. Year by year, ever more lights in these cottages are turned off, taking the prices for them higher and higher, pulled up by money from Edinburgh, Glasgow and London. It is hard to live here. Wages are a third below the Scottish average, but prices come out a third higher.

Where the road passes a ruined Hanoverian fort, we pull up for a chat to the builders. They hear my English voice: “Are you here to buy?” An old cottage is coming on the market. But even the old foreman is not from here. Neither is Alex: he was born in Glasgow. “There’s not a single person in this glen who’s from here. They’re all gone. We don’t know where they went. The people here, they’re almost all retirees — English folk, Glasgow folk, Edinburgh folk.”

The old fort looms behind us. “That’s where the redcoats were — we were like Ireland then.”

Alex begins talking about history, as I wonder whether all new nations must be based on victimhood. He explains that when this fort was built in the 18th century, a quarter of those in Scotland spoke Gaelic and lived with their own clans and culture. Nationalists like him believe that from this ruin, beginning with the Jacobite rebellions, there is one story line that matters: the conquest of Gaelic Scotland. Lairds who fought the redcoats were executed, and their land possessed by the Crown, gifted to loyalists. Gaelic dress and Gaelic schooling were forbidden, this way of life finally broken in the Clearances.

“It’s awful, just awful, what they did.”

But there is one crucial difference between both crushings: betrayal. Unlike Ireland, Gaelic Scotland was broken by its own lairds — the clan chieftains tenants once revered, now turned Westminster peers. When Queen Victoria was crowned, a fifth of Scotland spoke Gaelic, by her death, only 5 per cent, mostly in the Isles, still could.

“You know what?” Back in the car Alex is talking about his grandfather. “He was a keen walker, he was a good man, and he walked over Scotland. And I was at my parents’ recently, and I found his diaries. He’d written in there: ‘It is my firm belief having walked through the Highlands that the Clearances were the right thing. This land cannot sustain life for a population of any size.’ And I just thought, oh my God — how could you have thought that?” History is a constant, rolling judgment.

Plantation Ireland, with its bards and rebels, was never truly conquered. Clearance Scotland was utterly vanquished. Helpless, with no one to rally around, the peasants of the Sutherland estate turned to attack the sheep, not the landlords, wildly, but more pathetically, trying to chase away the herds replacing them. Gaelic Ireland was to Britain always something dangerous, to be despised. By 1822, the first time a British monarch had been to Scotland in nearly 200 years, Gaelic Scotland was so smashed it could be sentimentalised. George IV was presented with a kilt. Scotland is not just what it remembers; it is also what it forgets. The old British myth forgot the Highlands for the Anglicised Lowlands, which became the great industrial cities of their age. The new Scottish myth forgets the Victorian Lowlands; its theatre of Scottish history is the Highlands alone.

Driving back in lowering gloom, I sit listening. “The SNP is not an ethnic nationalist party, it’s a civic one.”

Alex has been in the volunteer fire brigade. A few years ago, at 1.30am, their pagers had rung, bleeping, bleeping — emergency in the grounds. Panting, the boys ran and raced to the grand mansion. It was the laird’s son. He was having a party. “And he was there, surrounded by all these bottles of champagne and boys and girls and he went, I’ve run out of water for me guests, can you refill me tank? The boys did it, and he gave them a glass of champagne, and a crate of beer. Those were the right sweepings off an Englishman’s table, I tell ya.”

But that very same laird claimed an old clansman’s lineage. The first thing they tell you is that Scotland is not England. And they tell it you often. But in terms of class, Scotland is a comically exaggerated version of England. In Scotland, the moment you become posh, you become essentially English. The gulf of worlds is greater, the accent-shift more grating, and so is the sense of us and them. This is why Scottish nationalism is not about blood. Scottish nationalists don’t care if the ancestors of a Harrovian lord from the King’s Road led the charge in 1745. At first glance this is something utterly British, and at its heart about class. But this is also the only nationalism that could be expected of a nation betrayed by its elites. The only thing you need to know is that in Scots Gaelic they call the Highland Clearances the “expulsion of the Gael”.

The road passes the tracks of the Caledonian sleeper north.

Alex is dreaming, imagining what the lairds would say to land reform. Everyone in the Highlands knows how the lairds tell you their family history, squiggly family trees on paper rolls, stretching back hundreds of years. They imagine that if you confront the landed they would issue a plaintive gasp: “Our family has been here for 300 years.”

Alex flickers, angry. For everyone else living on the moor, a long, long time means nothing at all. The car drives back to the real Highlands, a land of dismal bungalows, mini-roundabouts and co-ops, not turreted Victorian follies.

“That old laird, from the estate, we remember him, back in the referendum, he had his huge big poster: “Delighted to be united”, or whatever. But then six months later, he sold up. There were families living there, they’d been living there and farming there, and one day to the next, the new owners, some billionaire, went ‘Leave’. I tell you, it was like a new Highlands Clearances for them, it was.”

One farmer committed suicide when the old laird sold up and the new oligarch owner gave him notice to get out. “That family had farmed that land for three generations. The Clearances — the power to turf out families because you could — that’s never stopped. This is mental crack.”

Morning light. I am standing on the platform at Rannoch station, where in Trainspotting the junkies come for a breath of fresh air. A reddish wasteland ripples out from the platform into nothing. The deerstalker is waiting for me. We drive up to hunt with the guns.

“When they began, the SNP,” the stalker mutters, “a lot of people thought they were good. To, you know, end the English rule. A lot of people liked it. A lot of people, they rise to them, against the English landowner. But now, we know they are going to interfere with our way of doing things, those of us up the hill don’t like them at all.”

Trudging over a Jackson Pollock landscape of yellowy lichen, sprouting tufts and reddish moss, the bog sucks, like lips, on my boots. There is no horizon. Mist surrounds us in white. “There’s the beast.” Spectral shapes of stags emerge, gallop, then disappear. Binoculars pointed, the stalker hunts them with his eyes. “They’re not like us. They only see in black and white. There are no colours for them. Only shades of grey. That’s why they can always see us in the fog.”

The stalker points down to Loch Rannoch. Most of the landlords here are now foreigners: Belgians, Swedes, Dutch, Germans. Further afield are Danes, French, Arabs. “The worst thing that could happen,” he says, “would be the politicians in Edinburgh to destroy the lairds, who really are Scots, part of us for centuries, and hand this to some oligarchs. Or even worse, the politicians could destroy the sporting industry with an enormous and jobless national park.”

The longer I spend in the hills, the more stories I hear. The farmers mumble about how the sheep always return to the ruined villages, but they can never understand why. The electricians refuse to go into one of the stately homes alone, because they feel they are being watched. Some of them, point out the local SNP, are the old Hanoverian barracks.

I find tension round the loch. The rise of the SNP is unsettling the tiny rural communities around the great estates. Most of the people interviewed are too afraid to give their names.

If they support land reform, they say they could lose their jobs. “He’ll sack me on the spot if he knows I want his land for the people.” If they oppose independence, they say the local SNP would be aggressive down the pub. “They’re so hotheaded, I say I’m not into this plan, they call me an English stooge.”

Country lanes have been filled with scandal. During the referendum, according to the campaign organiser, 80 per cent of the rural “Proud To Be Scottish, Delighted To Be United” posters were burnt down or defaced. Vandalism injected a distrust between the cottages which did not exist before. I find creeping unease in the country homes. Most of those I speak to who belong to these grand lodges, lined with roebuck skulls and antlers, are unsettled, and decline to speak on the record: “It’ll make things worse, me speaking in an English accent.”

In these grand lodges, they sense nationalists’ vitriol for aristocrats and disdain for private property. One landowner in Jura, who happens to be the Prime Minister’s stepfather-in-law, has warned the SNP may bring about a “Mugabe-style” land grab. There is a sense of battening down the hatches.

“We’re a family. We’ve lived here for centuries. We know and love this village. We care. But if they decide to tax us till the pips squeak a new community land trust won’t pop up but some sheikh who won’t give a damn,” is a common refrain.

The landowning families around Loch Rannoch know that the SNP’s proposals rejected at conference were not terribly worrying. What unnerves them are the yells from the new members to put their estates through a meat-mincer and call it land reform. Like everyone else in Scotland, they don’t know what direction the swollen, empowered ranks of nationalists are marching in: “British politics is so unstable. In ten years they could be Scottish New Labour or they could be Scottish Sinn Fein.”

On the lochside, on a long tendril of land surrounded by darkening water and sky, it is easy to see Scotland in caricatures. The same goes for landowners. The majority of them live in Scotland, although the absentees are the ones with the greatest acreage. And there are different kinds of aristocrats. Some of them have fortunes, others are clinging on. Some only come to Scotland for shooting on the Glorious Twelfth, while others, like Donald Cameron the Younger of Lochiel, who with 72,000 acres is one of the largest landowners in Scotland, have made their lives in Edinburgh. SNP activists do not see things in these shades.

Drained after the fog and the moor, I sit down and call Donald Cameron in Edinburgh. His voice laments the stereotypes: “I find this dialogue very depressing. And the picture is much more nuanced than people would expect. Various people have set up this, I think, false argument: it’s not private land equals bad, community landowners equals good. I feel part of my local community. I don’t feel separate from them. These simplistic divides aren’t there in real life. When you get to an estate you see a vibrant business that is employing local people and attracting them to the area. And were they not all tarnished with the brush of landowners the SNP would be hailing them for their enterprise.”

Down the line, I tell the Younger of Lochiel what I’ve heard from Alex and others in the Cairngorms.

“The history has entered popular myth,” he replies, “and there’s no doubt that the Clearances are a great stain on our history and reputation. But at the same time we can’t be shackled by it. And that’s my view. We are in 2015. And life goes on.”

On the night train heading south, as the windows shudder and fill with lights from passing carriages, I drift back to the two statues by the sea. Above all, I think, it is truly simple for The Emigrants and nationalist memory to win over the Duke of Sutherland and memories of Britain. The Scottish role in the conquest of India, and the Protestant mission, are not glorious stories any more. And in that absence, the Clearances loom largest.