SUNDAY TIMES WEB DESK: Asked whether he would deny that May had told a meeting of her cabinet that the proposal was not feasible, the spokesman said: “The way you’re presenting it to me… I wouldn’t represent it the way you are to me.”

The spokesman instead referred to a statement from the Brexit department, issued on Monday after talks with EU negotiators in Brussels, which said:

“The Secretary of State (Barclay) discussed alternative arrangements and his ongoing work with the Alternative Arrangements Working Group. While the Commission engaged seriously with these proposals it expressed concerns about their viability to resolve the backstop.

“We agreed to keep exploring the use of alternative arrangements – especially how they might be developed to ensure the absence of a hard border in Northern Ireland on a permanent footing, avoiding the need for the backstop to ever enter force.”