Trade disruption could return if British holidaymakers head for European summer breaks, the head of Britain's biggest port said, calling on the UK government to urgently reconsider funding to redevelop Dover to prevent long-term damage.
Dover is a hugely important port for Irish exports and imports into the continent, despite the opening of direct sea routes to France.
But the UK government dropped a travel quarantine requirement for fully vaccinated cirizens this week, potentially increasing the number of vehicles that could descend on the port over the summer holiday months.
A pre-Brexit trade rush led to 32km queues, but Doug Bannister, CEO of the Port of Dover, told Reuters the site had so far managed the switch to customs checks well, after Britain left the EU trade bloc at the end of 2020.
"That's because we haven't seen the demand for tourists coming from our facilities, as we would normally expect to see," he said on a bright sunny day as a ferry departed for Calais.
"There will be longer transaction times and more processing," Mr Bannister said, if there was a rapid return of passenger cars to Dover, which was used by some 2.4m trucks, 2m tourist cars, and 74,000 coaches in 2019.
Britain's transport minister Grant Shapps has said that new vaccination status checks could also cause queues at airports and ports, including the busy cross-Channel route.
British industry had warned in the run-up to Brexit — which took Britain out of the EU's single market and customs union — that the supply chains could be strained to breaking point.
Even the UK government said that some 7,000 trucks could back up from Dover if they failed to fill out paperwork correctly.
Instead, a December rush to stockpile goods in the country meant trade dropped off in January and enabled manufacturers and logistics groups to adapt to the new demands.
Now it is asking again, and for more, to build increased passport checking capacity, to reroute some traffic and make it easier for trucks with the wrong paperwork to leave a site that is sandwiched between Dover's towering white cliffs and the sea.
Dover is also unclear on what changes it would need to make, if any, before the introduction of a new EU security plan, the Entry-Exit System, that collects data on the movement of people.
Mr Bannister said it was only logical that the UK government should fund the redevelopment because increased customs checks formed part of the Brexit deal it had negotiated.
He said an "alternative funding mechanism from government" was now needed.
A spokesman for the UK government, which has given money to the local area and built nearby customs processing centres, said it could not comment because of the legal proceedings, which it said it would "robustly" contest.