The new charges are particularly heavy for small businesses, which will simply stop exporting to Scotland as some have already done to Northern Ireland.

The Irish Sea border exists to carry out the checks that would be too incendiary to carry out on the invisible border between Northern Ireland and EU member Ireland.

But there is no convenient ferry crossing on the 96 miles between Marshall Meadows Bay on the east coast and the Solway Firth in the west to channel checks.

The only solution to convince Brussels that the integrity of its single market would be protected would be a hard border between Scotland and England, complete with checkpoints.

Even that would not protect EU territory from a stray English cow crossing the border without the Brussels-approved ear tag.

“Magic Thinking”

The SNP could argue that technology and digital customs procedures could alleviate border frictions. But Brussels dismissed ideas such as “magical thinking” when the UK suggested them as possible solutions for the Irish border.

This does not take into account any measures the UK may decide to impose on Scottish products in response.

The EU will be less flexible with Scotland than it is with the island of Ireland. Scots will not benefit from an EU member state like Ireland which demands special treatment.

Outside the UK, suppliant Scotland will not be able to demand waivers from Brussels rules as it begins a membership process that may take decades.

He will have to promise to join the euro and abide by EU fiscal rules on budget deficits, if he can meet the membership criteria.