LONDON — Britons got a taste of what a food shortage might look like during the coronavirus pandemic, and it does not bode well for Brexit.

The coronavirus crisis has seen worried Brits panic buy toilet paper and food as the virus sweeps across the globe. For most, it is the first time in living memory that food availability has been reduced, caused by the just-in-time supply chains being unable to cope with the sudden increase in demand, despite no shortage of supply.

Research from consumer analysis firm Kantar found supermarket sales for March topped those usually seen during Christmas, with an average household buying five days’ worth of extra groceries. Social media was awash with images of bare shelves.

Experts have warned that the U.K. public, drawing on such coronavirus experiences, could eschew their previous complacency around Brexit and rush to the shops to stockpile again as the transition period draws to a close.

When a no-deal Brexit loomed last year, with warnings that disruption at the U.K. border with the EU could lead to food shortages, only a small number of people listened. Twice, Britain came within days of a no-deal departure, but an army of shoppers did not descend on stores.

“In a no-deal Brexit situation, with tariffs and regulatory checks, some supplies could stop overnight” — Dominic Goudie, head of international trade at the Food and Drink Federation

Things will be different this time, experts say, and not just because there will be guaranteed disruptions at the EU-U.K. border, deal or no deal. Consumer psychologist Dr. Cathrine Jansson-Boyd said Brits will “definitely” begin panic-buying again, assuming they have not run out of their coronavirus stockpiles. “They will think, ‘I’ve been through this recently, I’m worried about it, let’s start thinking about what happens if this becomes reality,’” she said.

Erik Millstone, a University of Sussex professor with expertise in food safety, agreed. “It is clear that when people anticipate shortages they rush to the shops to try to stock up, and exhortations [by the government against this] on their own have been proven insufficient.”

A Cabinet Office spokesperson said: “We are confident in the resilience of our supply chains. There is no need for citizens to stockpile now or in the future.”

Not quite in time

The coronavirus outbreak highlighted the problems with the so-called just-in-time supply chains. In the current system, stores hold little in the way of stock beyond what is on the shelves and in transit. Supplies are delivered regularly in small quantities, meaning costs can be kept low and problems with products can be rectified easily. That is why the pandemic led to in-store shortages.

Such a "lean supply chain" for groceries doesn’t have any flexibility to deal with situations of panic-buying, said Dr. Sam Roscoe, a senior lecturer in operations management at the University of Sussex Business School.

“A just-in-time philosophy is all about standardization, repetition and having known demand. But with Brexit and the coronavirus, that demand is just not known and [the industry] can’t forecast for it,” he added.

Dominic Goudie, the head of international trade at the Food and Drink Federation, insisted the supply chain is “actually pretty robust,” but warned that “the Brexit impact on the supply chain would be worse than the coronavirus.”

“In a no-deal Brexit situation, with tariffs and regulatory checks, some supplies could stop overnight,” he said. The government has confirmed that the new trading regime with the EU will involve new customs forms and checks, raising the prospect of big delays, during which fresh food could rot at the border.

Another concern is that delivery drivers who do not have the correct paperwork after the end of the transition period could end up stuck. “[With the coronavirus,] some drivers are worried that if they drive into another country they could be at risk of infection or the borders could close and they could be stuck there,” Goudie said. “In a Brexit situation ... drivers could get stuck if they do not have the right paperwork or approvals. Some drivers might decide entering the U.K is more trouble than it’s worth.”

Recipe for disaster

There is little in the way of workarounds to the problem. Ahead of the earlier Brexit dates in 2019, some stores did build a stockpile of goods, but Goudie said it's not a perfect solution. “There is only so much you can store, especially in safe and hygienic conditions,” he explained. “And if the end of the coronavirus crisis feeds straight into the peak Christmas period ... it’s a recipe for disaster.”

Millstone, from Sussex University, said the coronavirus crisis should “influence the policy preferences of the government in its negotiations about the future relationship with the EU.”

He dismissed suggestions that the U.K. could import fresh produce from elsewhere to account for any loss from EU supply chains. “Many other places have health limitations and could be at even greater risk of disruption,” he said. “It is therefore a bad idea to discard or weaken links with continental supplies.”

He added that the U.K. would be unable to feed its population through domestic production alone without at least a year of planning, and that diets would have to change drastically and would not be sufficient for health purposes.

Shadow Environment Secretary Luke Pollard issued a thinly veiled warning to the government. He said after the experience of the coronavirus, the public will “want politicians to make food supply even more robust — not more precarious.” He added: “Certainty will have a greater political currency for people because of their lived experience during the virus.”

CORRECTION: An earlier version of this article misspelled Dr. Cathrine Jansson-Boyd's name.