THIS column is going to be about a subject bound to come up for SNP campaigners in any rural seat, but especially in those we have to win back from the Tories in the north-east and south-west of Scotland – all 13 of them.

The Tory Brexit, if and when it comes, will at once bring an end to the operation of the Common Agricultural Policy, which has kept our farmers afloat ever since we joined Europe in 1973. Without it, in fact, most of them would long ago have gone bankrupt, because the great majority of Scottish farms run at a loss.

The latest figures show the average farm earns £149,000 a year yet bears costs amounting to £168,000 a year. Dairy farming makes a reasonable profit but all the other types of agriculture lose money, or would lose it without the subsidies they get, especially in remote areas.

After Brexit, there will be no escaping from this train wreck. After independence, it will become even more mangled and deadly, unless Scotland manages to scramble back into the EU in short order. If, on the other hand, that process takes a longer time, there may not be much Scottish agriculture left, or anything recognisable as such.

The CAP was essentially set up to serve the interests of peasant farmers in the original six member states, with the high costs paid by food consumers. The UK, as a latecomer, always fitted awkwardly into the structure.

This did not matter too much because peasant farming continued to die out anyway and was replaced by agribusiness on a huge scale, intent on capitalist exploitation of the land rather than on preserving quaint rural society. That is why, if you drive anywhere across the North European Plain today, you will see few farms or fields, only expanses of single crops being gathered in by combine harvesters huffing and puffing away on the horizon.

While joining in the CAP, the UK all the same continued to oppose its more irrational excesses and, on our own soil, to adapt it somewhat to local conditions. One result today is support for innovative investments in niche markets, which is, in practice, handed over to wealthy and progressive English farmers. In this way, they keep ahead of the game through advanced technology and new products – the same way they have survived in adverse global conditions for the past 180 years.

A second result today can be found in the blanket subsidy which is the norm in Scotland and keeps farmers going who are too straitened and stretched for venturesome investments.

I think the big English farmers will survive the fresh upheaval of Brexit in reasonably good shape. Their 45 years of EU regulation have made them producers of the highest quality, offering the world meat and other products second to none. Even if President Trump prises open our markets, I hope UK consumers will resist buying the products of American farms which are demonstrably filthy cesspits of animal disease, feebly controlled by chlorine washes.

By contrast, I fear Scots farmers are facing a massacre. Most of them will go out of business. The cost of farmland will suffer a disastrous fall. This year, it has been selling on average at £4000 an acre, and next year we might expect the figure to halve at least. What follows then? The most likely sequel is that the land will be bought for a song by European agribusiness. The French conglomerate, Carrefour, already has link-ups with UK retailers, Tesco in the High Street and Ocado online. It will see here a way into every shopping basket in the UK. Goodbye Waitrose, farewell Morrisons! Maybe we’ll be feeding French in future, with foie gras and frogs’ legs on the family table.

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What makes Carrefour such a giant is that it forges backward as well as forward links, that is to say, it likes to construct chains of supply stretching not only to the consumer but also from the producer, following the best modern multinational practice in every progressive industry. In Scotland, it would cost hardly a month’s profits to buy up all the land in the Highlands and Borders that came on a wrecked market-place. To maximise future production of our incomparable cotelettes d’agneau or rotis de boeuf, Carrefour would then need to clear the human population. Incredible? But it’s happened before.

History could repeat itself because, in a gruesome kind of way, this would be a rational use of the poor land – the mountain, moor and rough grazing – of which the Highlands and Borders consist. We can find parallels in other infertile parts of the world, the Australian outback or the American Wild West. These, too, are fit only for raising sheep and cattle. Or rather, the beasts raise themselves. The farmer turns them loose to look for their own fodder, and back they come all fattened up for slaughter. In the barren landscapes, no other human presence is needed.

In Scotland, we already have foundations for the same system. The largest landowner in the country is the Scottish Government. It has vague plans to repeople its holdings, but these are only inching forwards – partly because there is no money and partly, I suspect, because native Scots’ desire to give up urban life and eke out an existence in a howling wilderness has been absurdly exaggerated (gullible foreigners are more likely candidates). The second largest proprietor is the National Trust, which by definition does not allow its lands to be inhabited.

Then come two more interesting cases. Anders Povlsen is the Danish billionaire who, on estates stretching from Aberdeenshire to Sutherland, has set out to “restore our parts of the Highlands to their former magnificent natural state and repair the harm that man has inflicted on them”. This means a historic change, and self-evidently it could only be contemplated by a rich man over a vast area. It would be impossible on 50 acres. And then, just pipped at the post by Povlsen, comes the fourth largest landowner in Scotland, the Duke of Buccleuch, running an estate of the traditional kind and much abused by land reformers.

But after Brexit the reformers will need to change their tune. For a long time their ideal has been the smallholding, but smallholdings are going to die out in the new conditions. You can see the process already at work in the crofting system, born of the same idealism but today, despite detailed regulation, fast degenerating.

The big estate is going to become the norm, the indispensable norm, in the north and south of Scotland. Hatred of the big estate will be hatred of any kind of economic activity and therefore of population in these regions. Wilderness may be fine, but is a human void really our aim?

All this is further complicated by the prospective political tussle after Brexit, when there will be a push for Scottish agriculture to be controlled from London rather than Edinburgh once the relevant powers return from Brussels. To Boris Johnson’s Cabinet this will no doubt look like the right way to deal with such an insignificant sector.

The Scottish Government will oppose the power grab, and the controversy will get caustic. But our case would be stronger if in Scotland there were more realistic analysis of the prospects, the risks and the opportunities, and less knee-jerk resentment of people who just do the job somebody has to do and run a big estate.

Plenty to talk about, then, during the election meetings in the village halls these dark, cold winter nights.