Boris Johnson, who met Gordon Brown yesterday, believes that the EU wants to keep Britain in the single market

Theresa May and her Brexit “war cabinet” have agreed a new fallback position on the Irish border that could preserve elements of the customs union if Britain cannot strike a deal on its preferred post-Brexit trading plan.

Ministers including Boris Johnson, Michael Gove and David Lidington discussed the “backstop” plan for Northern Ireland that will come into force if Mrs May’s blueprint for customs arrangements collapses.

Mrs May has rejected an EU version of the backstop that would have guaranteed no infrastructure on the Irish border and committed the UK to maintaining regulatory alignment between Northern Ireland and the Republic. This would have meant Northern Ireland and the rest of the UK having different rules, raising the prospect of a border in the Irish Sea,