It’s a very short list of things blocking a deal on the UK’s withdrawal agreement from the EU, and it’s easy to understand why Northern Ireland is at the top of it.

The future of the Irish border is tied up in centuries-old tensions borne of culture and identity, as well as hard economic and political realities; both sides believe they are justified in refusing to give ground.

But the same could be said about the next thing on the list, less talked-about and much less understood: feta cheese. Greece’s salty signature foodstuff could cause the UK’s Brexit deal to crumble, as ridiculous as that sounds.

Feta cheese, as seen on sale in a shop in Athens, must be made in Greece from ewes and goats milk, under EU rules (Picture: Aris Messinis/AFP/Getty)

Not on its own, of course: the fate of feta is only part of the row over the EU system of geographical indications (GIs), which protect food and drink products linked to specific regions of Europe, or with particular traditions of artisanal production attached.

Under EU rules, only feta produced in Greece from the milk of local ewes and goats can call itself feta. A cheese by any other name might taste as salty, but it can’t be marketed using the well-known name, or indeed any imagery suggesting a link to Greece.

When the Greek government first sought EU protection for feta in 1996, there were objections from France, Germany and Denmark, with some reason. Feta only means ‘slice’, and there is no particular geographic focus to production; like many Mediterranean foodstuffs, it has cousins spread across the former Ottoman empire.

But food is as fundamental to identity as any aspect of culture, and the cheese is as much an internationally recognised symbol of Greece as the Parthenon; indeed, if Greeks were asked to choose between getting back those missing marbles or giving away their exclusive right to feta, I wouldn’t want to guess which way it would go.

Feta’s history is as old as myth: when he wasn’t gobbling lost sailors, the Cyclops is described making cheese from ewe’s milk in Homer’s Odyssey. Mass production has yet to completely banish memory of the ancient methods.

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In the summer, shepherds would gather their flocks near cool, snow-fed mountain lakes and caverns to milk the ewes and hang the curds in cloth bags. When the young cheeses, salted and matured in brine, were ready for market, the barrels were loaded onto mule trains that plodded into the valleys. The animals knew the path, so watching over the cargo was childsplay: at age eight, my grandfather was put on top of the lead mule for the journey down the slopes of Mount Giona, overlooking the ruins of Delphi, tied with ropes so he didn’t slide off if he fell asleep.

Protection for artisanal goods carries real economic significance for producers, but in a world made anxious by rapid globalisation, they also represent an anchor point of reassuring localism. It’s strange, therefore, that Brexiteers find such protections for cheese so ‘grating’.

“Why should we ban eg feta cheese from the USA, which tastes at least as good as EU feta and was introduced into the US by Greek-Americans and with same cultural heritage?” the former trade minister Greg Hands posted on Twitter at the weekend. Another Tory MP, Marcus Fysh, was equally cheesed off. “Brits could be free to eat tasty and cheaper Halloumi and Feta made in America,” he tweeted, before falling into error and tautology by adding that the UK could soon be selling “excellent English sparkling Champagne in Asia and Americas”. All Champagne is sparkling; none of it comes from England. It comes from a region called Champagne, in France, hence the name.

Neither MP explained how a US import shipped across the Atlantic will manage to undercut a product available in most supermarkets for less than £1.50 – and if cheaper cheese is the Brexit dividend, you’d think they would be a bit sheepish about it.

But as trivial as it sounds, there’s a good reason why recognition of GIs after Brexit remains unresolved while weightier issues like citizens’ rights have been agreed. For the UK Government and Brexiteers, a free trade deal with the USA is the ultimate goal, but that prize is slipping away.

Under Theresa May’s Chequers plan, the UK would effectively remain in the European single market for goods, and American agricultural produce in particular has always struggled to clear EU hurdles – think about the controversy over chlorine-washed chicken and hormone-fed beef.

To Downing Street’s embarrassment, ahead of his visit to Britain, Donald Trump himself warned a US-UK trade deal would be much more difficult, if not impossible. So Brexiteers want to dismantle one barrier to US produce – the GI system.

It seems an insignificant gesture to a tiny American industry – it’s feta, not Ford. But Trump’s warmongering trade policy makes clear that he values symbolic wins in ‘heartland’ industries more than the economic bottom line.

This week, US and Canadian trade negotiators are locked in last-ditch talks to save the North American Free-Trade Agreement. Trump has taken the talks to the wire in order to grind a tiny concession out of the Canadians – the removal of production caps that stabilise dairy prices. Getting American ‘feta’ into British supermarkets would be an even smaller victory, but may still be worth a tweet from the big cheese.

Brexiteers like Hands and Fysh should beware, though – and not just because the prize can’t justify collapsing talks with the EU. Not including wines and spirits, 80 British foods have GI protections, and would be open to competition from the US (or even Europe) if the UK ripped them up. ‘Cornish’ pasties are already produced in America; could Stornoway black pudding be next?

Scotch whisky is also recognised under the EU GI scheme, although it also claims historic legal protections in both the UK and the US. In the uncertain environment of a no-deal Brexit, however, no food and drink producer anywhere in Britain would seek additional competition and an erosion of the brand. On the list of things that could make a meal out of Brexit, the cheese stands alone.

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