The closure of the UK-France border before Christmas over the new strain of COVID-19 highlighted the rapid knock-on impact of any delays.
Now, with the Brexit transition period ending on December 31, there are fears that fresh hold-ups will begin again. That's because — regardless of the fact a post-Brexit trade deal has been agreed — new customs rules apply from January 1.
Brexit means London and Brussels now have different customs rules and regulatory standards, meaning border checks are necessary. They will apply to UK imports into the EU, but checks on goods coming the other way will be phased in over six months.
Nevertheless, there are concerns about the impact of any delays on imports from the EU, especially since that's where a majority of the UK's fruit and vegetables come from.
"Peppers, aubergines, cucumbers, tomatoes, broccoli - that’s all going to be ok," said Vernon Mascarenhas, commercial director at UK-based Nature’s Choice food company.
"But the finer, the more delicate, the salad heads. Anything above 48, 56 hours [journey time to the UK] we will then start to see a deterioration in the crop and I’d go as far as to say that we might need to rethink things like baby spinach which has got a very, very short shelf life. Baby spinach would not make it, even on a chilled lorry for three days."
Shane Brennan is the chief executive of the Cold Chain Federation. He speaks on behalf of the people who drive chilled trucks from Europe to the UK.
"The phrase is border-ready," he said. "Having all the paperwork in place depending on the products you’ve got in your vehicle and they’re ready to move through the border... If there’s any kind of lack preparedness, that will lead to a delay to that vehicle. And if there are any gaps in their paperwork, they will literally be stopped and turned around. That then creates a knock-on effect. It doesn’t take very much of that to slow the whole system to start to slow down quite dramatically. Small delays, vehicle by vehicle, leads to long delays for everybody else."
British supermarkets are preparing as best they can. In the case of goods with a long lifespan that means stockpiling. But the chairman of Britain’s biggest supermarket chain Tesco has said that shortages of fresh food can’t be ruled out for a period of weeks, or possibly months.
People in this industry see delays as a certainty rather than a risk. The real uncertainty is how long they might last.