On Friday, 240 experts from 40 countries descended on Viseu in northern Portugal for the World Cheese Awards. The judges sampled throughout the day, with a washed-rind raw sheep’s milk cheese from the host country, queijo de ovelha amanteigado, named the best.

But throughout the afternoon, the British contingent noticed something strange: gaps on several of the tables. Britain’s cheeses, it transpired, hadn’t passed customs, and were robbed of the chance to compete with the world’s best.

Occasionally some countries’ cheeses don’t make it, said John Farrand, director of the Guild of Fine Food, which runs the event. But Farrand added the Guild is granted a special licence each year to import cheeses, and British cheesemakers complied with all the conditions.

On Friday morning, however, it became apparent that the cheeses hadn’t been cleared. “The reasons are unclear to me, even on Friday we were still fighting to get some clarity and clear instruction on what wasn’t right, but we had no success,” Farrand told the Observer yesterday. Up to 252 cheeses from 67 makers may have been affected.

Farrand pointed out that cheeses from countries that were “typically much more difficult to import for the judging”, such as those from South Africa, Japan and several South American nations, were able to compete. While the exact cause is still unknown, leaving the EU has made things trickier, Farrand said. “Before Brexit, this wouldn’t have been a thing. That’s a fact.”

Judge James Grant, co-founder of the Real Cheese Project, said: “It’s really devastating. The UK’s going through an incredible change as far as cheese is going. There’s an incredible amount of hard work from these cheesemakers who are putting handmade artisan cheese back on the map. It’s really, really sad.”

Grant added that since Britain left the EU, importing and exporting cheese has “become more challenging, with the increase of bureaucracy and red tape”. It’s a view shared by Jane Quicke, of Quicke’s cheddar in Devon. Speaking from Viseu, Quicke told the Observer that since leaving the EU, “we have had cheese held up, rejected and wrongly charged tariff countless times. Our cheese has to travel from Devon to Preston to the Netherlands instead of going straight to the end customer like it used to.”

Quicke added she was “so sad that many English cheeses, including ours, were not able to be judged alongside our international counterparts, but I am not entirely surprised.”

For Grant, it wasn’t just that Britain’s cheeses weren’t able to receive any medals – one or two often make the top 10, and a British cheese called Cornish kern last won in 2017. But each of the 4,786 cheeses judged receives feedback, giving makers a chance to learn and improve their product.

“Hundreds of British cheesemakers have worked so hard and are so proud of what they do.” Grant added that the World Cheese Awards can “turn people’s lives around,” and predicted the Portuguese winner’s life would “change overnight.” For the cheesemakers to “receive a blow like this within hours of the largest cheese competition about to open was a hammer blow not only for British cheese, but cheese as a whole.”

Sam Wilkin, part of the team behind yarlington and rollright, was “very disappointed” they couldn’t compete. “We fancied our chances,” Wilkin admitted. “What it really shows is that it’s very hard to export cheese post Brexit. The Guild will have done everything in their power to make it happen, they will have dotted Is and crossed Ts, but if someone at the border decides something isn’t quite right, or they misinterpret a piece of paper, the whole thing falls apart.

“We are really disappointed to not compete but it raises the more important question of what kind of damage are export controls with our nearest trading partner doing to our industry?”