Almost four years after Johnson promised the fishing merchant the French would be desperate to buy his fish, the business has seen sales plummet 30% and export costs rise by as much as £3,000 a week.

“We were sold a lie by Westminster,” he said in a break in bidding at the market, one of Europe’s largest, but operating at less than one quarter capacity when The National visited.

James Withers, chief executive of Scotland Food and Drink, said the situation is a ‘real crisis’ for exporters.