Philip Rycroft, the former head of the Department for Exiting the European Union (DExEU), said the solution was “the one to watch” as Boris Johnson desperately seeks a breakthrough. Mr Rycroft said the option was back on the table because the Tory Government was no longer reliant on the DUP’s support, having had their majority slashed since Mr Johnson entered Downing Streety. He said in Edinburgh yesterday the Government should consider creating a customs border down the Irish Sea, ensuring an open, invisible border can remain on the island of Ireland.
This is because the economies of Northern Ireland and the Republic of Ireland would remain roughly aligned, removing the need for customs checks on the border.
It was originally proposed by the EU but is strongly opposed by the DUP, who fear any delineation between Northern Ireland and Great Britain.
Mrs May said at the time the proposal would d”threaten the constitutional integrity of the UK by creating a customs and regulatory border down the Irish Sea”.
She said: “No UK prime minister could ever agree to it.”
Brexit news: The Irish border could remain invisible with a customs border in Irish Sea
Mr Rycroft, who led the department for two years until this March, said: “I think that is the one to watch.
“This is the border down the Irish sea. In many ways the simplest way of cutting the Gordian Knot of this.
“Impossible for Mrs May because of her dependence on the DUP.”
He said checks would take place on goods moving from Britain to Northern Ireland but not vice-versa.
Mr Rycroft said: “So Holyhead and Stranraer would become points of external export for both customs and regulatory checks.
“A lot easier to control point to point rather than a long complicated border.
“If I was to put money on this, depending on what happens if there’s a general election, I think that solution becomes very attractive to any government wishing to pursue Brexit.”
He said the alternative was a no deal exit, which would bring huge disruption.
He said: “This is a system with millions of moving parts.
"The Northern Ireland- Ireland border will be highly unstable. The UK will allow goods to come north without let or hindrance, pretty much.
“The south will require to put in place an external border of the EU. That is not a stable situation, and will have to be resolved very quickly.
“The more serious thing is the long-term economic dislocation. What we’d do is overnight put friction into our major trading relationship for both goods and services.
“That makes UK businesses less competitive selling into our major market.
“The same applies to EU businesses selling into the UK, but don’t forget that for them it’s about 9 per cent of their trade versus 45% for us.”