So it means implement standard procedures for a third nation.
In which case the UK government expects the flow could drop to 40-60%: source
Civil Service World.
"The government has predicted border delays even in its “reasonable best case” assessment of what could happen after a no-deal Brexit, according to the former official in charge of overseeing border contingency planning.
Karen Wheeler, who stepped down as director general for border coordination at HM Revenue and Customs in June, told a committee of MPs the government had estimated that after a no-deal Brexit the “flow rate” of trucks exporting goods to the EU via Calais could drop to 40-60%. She said assessment, part of the government’s Operation Yellowhammer contingency planning,
represented the “reasonable worst case scenario” – an outcome that is unlikely but “stands a significant chance of happening”.
In the reasonable best case scenario, the flow rate could be as high as 70-80% of current levels, she said. “But even in those circumstances, which seem just as unlikely as a reasonable worst case, you would still get delays,” she said."