The tense, three-way relationship between Britain, the European Union and Northern Ireland that leapt into the headlines last week following the abortive attempt by Brussels to invoke Article 16 of the UK-EU Withdrawal Agreement, is the single most dangerous legacy of Brexit. 

The Northern Ireland Protocol, of which Article 16 provides a last-resort get-out clause, challenges UK sovereignty at the same time as it divides Unionists and Nationalists in Ulster. It provides for an open border on what we must all now call the island of Ireland, keeping NI part of Europe’s Single Market, regulated by Brussels (with Dublin as its surrogate), rather than London. At the same time, it creates a customs border down the Irish Sea, rendering the province’s official status as part of the UK customs territory moot at best.