Theresa May faces a showdown with David Davis and other cabinet Brexiteers today as she tries to convince them of the merits of a customs plan that will keep existing EU tariffs.

Boris Johnson, the foreign secretary, Liam Fox, the trade secretary, and potentially Michael Gove, the environment secretary, are likely to raise their objections to Mrs May’s plan at a meeting of cabinet’s Brexit sub-committee.

The “customs partnership” option is backed by Philip Hammond, the chancellor, and Greg Clark, the business secretary, who hope it will avoid a hard border in Northern Ireland while maintaining the right to strike trade deals with non-EU countries.

An ally of Mr Davis made clear his objections to the plan, saying “he has made his scepticism clear in