“I can see there really might be a ban on the English Border crossing at this rate,” texted a Scottish friend in London. She had been hoping to come north this summer; no Bournemouth gallivanting for her. Short of wearing a bee-keeper’s outfit when she steps outdoors, she could not take more precautions. If attempts to pinpoint those carrying the virus northwards ever begin, she will probably come up clean.

Yet she is clearly unsettled at the idea of some kind of checkpoint on the A68, A7, or whichever route she might take. Speculation over testing or quarantining travellers between England and Scotland has been raised as part of a discussion of how to prevent infection from a neighbour with a higher incidence of Covid 19 than here. As a result, almost overnight the Border has begun to assume a significance it has not held for centuries.

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This pandemic might one day be viewed as a textbook illustration of the geopolitical fault lines across the UK. What was once a united front has splintered into four distinct nations, each with a different solution to the same problem. Nothing more starkly demonstrates the gulf between the laissez-faire ethos of the Westminster’s panjandrums and the commonsensical attitude at Holyrood than the ways in which they have eased restrictions.

The increasingly relaxed English regime appears to be fuelled by wishful thinking rather than science; the Scottish situation, meanwhile, is characterised by caution. Long before talk of checkpoints, this was already causing tension. When England’s routemap out of lockdown was weeks ahead of Scotland, John Lamont, Conservative MP for Berwickshire, Roxburgh and Selkirk, said those of his constituents close to Boris’s bailiwick were confused. Why did one rule apply to their very near neighbours, and another to them?

The answer seemed obvious – it was far too soon to relax – but the question vividly demonstrated the nature of this area. Many who live where Hadrian’s men boldly marched have a foot in both countries. They might work in one, and live in the other, hail from this side and have relocated to that. They could have family and friends in either camp, who remained out of reach for so long as the Scottish government prohibited meeting.

Those Border villagers who defied lockdown to visit a garden centre in Berwick were making a political rather than a horticultural statement. In this, they echoed attitudes since the days of the great reiving clans, who roamed freely on both banks of the Tweed. The Scottish and English kings were so appalled at the region’s lawlessness that, despite being sworn enemies, they worked in tandem to subdue it.

Given the way Borderers were treated by their lieges, it’s no surprise they thumbed their noses. These days, towns and villages are awash with folk from both sides, thereby creating a unique and strongly bonded region. Little wonder Unionism still pertains hereabouts.

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That there have been no deaths from Covid 19 in Scotland for the past few days suggests we are heading in the right direction. But there is a long way still to go. The First Minister’s aim is to eradicate the virus, not merely contain it. Seeing the daily tally of new cases and deaths in England, she seeks confirmation that the Prime Minister has the same objective. But, as she said earlier this week, without such assurances she fears England’s strategy is “letting it circulate at higher levels as long as it doesn’t threaten to overwhelm the NHS”.

If that is indeed the case, then monitoring passage between the countries is in some respects no different from policies implemented by a place like New Zealand. It initially imposed an outright ban on entry, followed later by quarantine on new arrivals. The problem is, as a devolved nation within a union, the consequences of such a step are potentially inflammatory. Some will view it as independence by stealth, a confrontational declaration of autonomy, or simply authoritarianism run rampant. Yet with a summer of staycations approaching, the repercussions of allowing untrammelled travel could be dire.

Before the prospect of imposing controls was mooted, people around where I live in Roxburghshire have been scowling at visitors from only a few miles away, let alone the depths of the English shires. When a couple of walkers dared ask a neighbour directions over the hills last week, they narrowly avoided a tirade.

The idea of the Border returning to its roots as a frontier inevitably creates a troubling sense of Them and Us, or Friend and Foe. Affront will be taken at any restriction on free transit between south and north. Presumably residents of Scotland who visit England will also be tested or quarantined on their return, making it a two-way injunction. Suddenly a weekend break in Northumberland looks a lot less appealing.

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Yet how exactly would it work? Is it only tourists who will be checked, or will those travelling back and forth for work, be they lorry drivers or business reps, also be subject to testing? Will every road, rail and sea route across the Border from Berwick to Workington be patrolled? Might we see a surge in midnight crossings over no-man’s land and rivers, four-by-fours finally justifying their existence and canoes retrofitted to ferry families plus their luggage across the Tweed?

As things stand, there have been no new cases of the virus in the Scottish Borders in two weeks. This beautiful, windswept district is starting to feel like a cordon sanitaire, a buffer between the haves and, if not precisely the have-nots, then a population beginning slowly but steadily to paralyse the disease.

Given our reputation as one of the sickest countries in Europe, we need to take every precaution to protect lives. Reimposing the Border as a barrier and guard would not be popular, and the war-time and military resonances are unsettling. Yet, in light of the high risk of contagion still posed by parts of the south, in the short term it would make sense. If the first thing passengers see as they arrive is not a sig welcoming them to Scotland but an NHS squad, then for the first time since 1547 – the last pitched battle between England and Scotland – the Border will have regained its old role as the country’s first line of defence.

All columnists are free to express their opinions. They don’t necessarily represent the view of The Herald.