One detail keeps getting lost in all the talk of a free-trade deal with the European Union after Brexit. For 180,000 UK businesses, it will be a logistical nightmare. No matter how big a bonfire of European regulations the government lights, Brexit will tie thousands of businesses in red tape as companies that now trade solely with the EU are forced to become customs-compliant.

Technically, selling UK goods into the EU is not global trade but “intra-community trade”, like selling apples from Kent to the people of York. Within the single market, “imports” and “exports” are not even classified as such but as “arrivals” and “dispatches”. Once outside, though, there will be a hard border — whether the UK remains part of the customs union,