Supporters of Britain’s rupture from the European Union have struggled to quantify benefits from Brexit, but when Donald Trump unveiled his schedule of global tariffs they finally had a number. It was the difference between the 20% levy imposed on all continental exports and the 10% baseline figure payable on British goods.
Sadly for the Brexiters, the gap closed a week later when Mr Trump aborted his plans. What the tariff schedules will look like at the end of the 90-day “pause” is no more predictable than any other feature of current US policy. There is no obvious concession from the UK government that might induce the White House to lower its 25% barrier against car exports, and the 10% rate on everything else looks non-negotiable.