Ring the bells, stage parades – there’s an armistice in the sausage war. Airlifts of chilled meats to Northern Ireland have been put on hold as the warring sides agree to a pause in hostilities. However, this is only an extension of the grace period before the full panoply of EU checks are imposed on British goods destined for the province.

Nicola Sturgeon has been uncharacteristically cautious on the sausage war, which might have seemed like an obvious opportunity to have a go at Boris Johnson’s Little Englander pretensions. It’s a lot littler now that Northern Ireland is no longer part of the UK, ha ha. But the SNP has been guarded in its commentary on the Northern Ireland Protocol. This is because an awkward realisation is dawning. In the sausage war, Scottish nationalists find themselves on the same side as Northern Ireland Unionists.

Breaking open the Protocol, and restoring free and unfettered trade between the province and the UK, is as crucial to the SNP’s independence project as it is for the leader-designate of the DUP, Jeffrey Donaldson. Indeed, I’d go as far as to say there isn’t a hope in hell of Scotland becoming independent if the European Union continues to impose a bureaucratic hard border between Northern Ireland and the rest of the United Kingdom. So, shock horror, Nicola Sturgeon is also onside with Boris Johnson.

The SNP’s line over the past five years, since Brexit shattered the dream of independence in Europe, has been: nothing has changed. When asked about the border that will appear when Scotland leaves the United Kingdom she has replied with her unique combination of weariness and pique: “Who wants a hard border? We don’t want a border, England doesn’t want a border. A border is not necessary.” Yet, of course, it is.

The SNP is intending to rejoin the European Union at the earliest opportunity and that will pose exactly the same regulatory issues that have caused unrest in Northern Ireland. However, hope springs eternal and Nicola Sturgeon insists that it will be possible for Scotland to rejoin the European single market while remaining part of the UK single market. It would anyway take a number of years for Scotland to meet the accession criteria for full membership of the European Union, which include an independent currency and central bank. In the meantime, it is reasonable to assume that Scotland would try to rejoin the EU single market first through the European Economic Area.

Either way, a border is inevitable – but the SNP believe it can be fudged, because England and the rest of the UK (whatever is left of it) does not want to see border controls and checks at Carlisle. The Northern Ireland Protocol presented a possible solution since it supposedly allowed the province to remain in the regulatory universe of the EU single market while also remaining part of the UK single market. At least, that’s what Boris Johnson and the UK Government believed. Brussels had other ideas.

Article 6 of the Protocol on “Protection of the UK Single Market” says: “Nothing in this Protocol shall prevent the United Kingdom from ensuring unfettered market access for goods moving from Northern Ireland to other parts of the United Kingdom’s internal market.”

That seemed to remove any prospect of a hard border. However, Article 6 goes on to say that Brussels will only use its “best endeavours to facilitate the trade between Northern Ireland and other parts of the United Kingdom, in accordance with applicable legislation and taking into account their respective regulatory regimes as well as the implementation thereof”.

In other words, we’ll not hesitate to impose whatever fetters we wish under the regulatory regime of the single market.

Brussels has interpreted the Protocol as essentially the creation of a border in the Irish Sea, imposing customs checks, not just on goods going to the Republic, but on goods destined solely for Northern Ireland. That Boris Johnson should have seen this coming and refused to accept it seems obvious now.

The UK appeared to believe that, because it was not imposing any friction on trade from the EU to the UK, Brussels would eventually follow suit. The UK, after all, is supposed to have a trade deal with the EU which ensures tariff-free and quota-free exporting. What’s their problem? Why would they even want to stop Sainsbury’s selling its sausages in Belfast?

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But the European Union is not an organisation devoted to free trade. It is an alliance whose prime purpose is to protect producers, especially in food and agriculture, from competition from non-EU countries.

This is why Brussels has not had a trade deal with Australia. Highly efficient, large-scale antipodean agriculture would undercut French “paysant” farmers – and Scottish hill and sheep farmers, too.

This protectionism is not solely through tariffs – indeed, most tariffs are low or zero. It is achieved through the application of friction: of bureaucratic obstacles. Endless paperwork, obscure rules, “sanitary and phystosanitary checks” and other impediments. These are designed to kill the will of exporters to enter the EU single market in the first place.

Just look at the plight of Scotland’s meat and fish exporters. There are no tariffs or quotas, but obscure rules, paperwork and checks make it almost impossible for them to guarantee swift passage of perishable goods to their biggest market. These rules and checks ought to be minimal because Britain has food standards that are equal to any in Europe. But that is not the point. They are there, not to prevent contamination or infection, but to prevent goods moving freely into the EU.

As the BBC has been reporting, in exquisite detail, these bureaucratic hurdles are being erected across Britain’s entire trading frontier. Food and drink exports to the EU have halved. Manufacturers are finding it is easier, and cheaper, to export to countries like America and Canada, with which we have no trade deal, than to the EU. This is unfair, economically counterproductive and reflects very poorly on the European Union’s trading integrity. But it was naïve to believe that Brexit would be cost-free.

It is equally naïve to believe that Brussels will be any easier on Scotland as far as border controls with England are concerned. They will apply the single market rule book. Nicola Sturgeon hopes that Boris Johnson will relent and effectively rejoin the single market, but he is most unlikely to do that.

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The apocalyptic forecasts of the Brexiters: epic lorry jams, a financial crash, medicines becoming unavailable etc proved to be overblown. According to last week’s polls the vast majority of Brexit voters still think they made the right choice in 2016.

But in Northern Ireland, the sausage war has inflamed the unionist community who fear the de facto reunification of Ireland. And the longer the European Union perseveres with its attempts to impose a border in the Irish Sea, the more it will alert Scottish voters to the dangers of a hard border with England.

Which makes nationalist Nicola Sturgeon the unlikely bedfellow of the toughest and most determined Unionists in the UK.