Boris Johnson has launched an unprecedented attack on the prime minister’s preferred option for a post-Brexit EU customs partnership, calling the proposed system crazy and saying it would not give Britain control of trade policy.

On a visit to Washington, the foreign secretary said a customs partnership, one of two options considered by the cabinet’s Brexit subcommittee, would be unacceptable.

Downing Street said on Tuesday afternoon that the prime minister retained full confidence in Johnson, but in remarks that could be interpreted as a rebuke, her official spokesman pointed out that the entire cabinet had signed up to her Mansion House speech in which she set out her plans.

While No 10 defended the business secretary Greg Clarke’s intervention at the weekend as entirely in keeping with government policy, May’s spokesman also refused to be drawn on whether the same was true of Johnson’s comments.

The foreign secretary’s comments give the strongest signal yet that he might be prepared to resign should Theresa May push ahead with the partnership option, under which the UK would collect EU import tariffs on behalf of Brussels.

The method would solve the problem of the Irish border, but Brexiters regard it as untested and impractical, opening the door to remaining in a customs union with Brussels.



Sources close to Johnson insisted he did not regard the customs union a resigning matter, pointing out that there were members of the cabinet who did not agree with Brexit but who had stayed put.

In an interview that put the backstage cabinet war out in the open, Johnson told the Daily Mail the method was “totally untried and would make it very, very difficult to do free trade deals”.

“If you have the new customs partnership, you have a crazy system whereby you end up collecting the tariffs on behalf of the EU at the UK frontier,” he said. “If the EU decides to impose punitive tariffs on something the UK wants to bring in cheaply there’s nothing you can do.”

Pro-leave cabinet ministers including Johnson prefer an alternative, maximum facilitation, or “max fac”, proposal, which relies on technology to keep border-checks to a minimum.

Downing Street has insisted both options remain on the table, though Brexiters have privately described the customs partnership as a “dead parrot” after their forceful objections at last week’s meeting.

Johnson suggested the partnership option, also known as the hybrid model, would not deliver on the result of the referendum.

“That’s not taking back control of your trade policy, it’s not taking back control of your laws, it’s not taking back control of your borders and it’s actually not taking back control of your money either, because tariffs would get paid centrally back to Brussels,” he said.

Johnson said the model would also force the UK into close regulatory alignment with Europe. “It only solves the Northern Ireland border question if you force companies to prove that an imported tariff-reduced good has been consumed in the UK and if you insist on complete regulatory alignment with the EU rule book,” he said.

“Otherwise if Britain chose to vary its laws in any way at all on goods and agrifood, then logically you would need checks at the border.”

May delayed a final decision on the preferred customs option after a tense meeting of the Brexit subcommittee last week during which the home and defence secretaries, Sajid Javid and Gavin Williamson, also expressed concerns about the plan, along with Johnson, the environment secretary, Michael Gove, and the international trade secretary, Liam Fox.

May, along with the chancellor, Philip Hammond, the Northern Ireland secretary, Karen Bradley, and the business secretary, Greg Clark, are said to prefer the partnership option.

Clark defended the model on Sunday, setting out how devastating customs checks would be for major employers such as the car industry. Frictionless trade was “something that we’ve made a public commitment to and we need to make sure that we get that right,” he said.

His intervention was taken as a bid licensed by Downing Street to revive a project that Brexiters outside cabinet believed they had forced off the agenda, though No 10 denied it was coordinated.

In his interview, Johnson said it was right that the cabinet were able to express different views. “Colleagues in cabinet have different concerns about different aspects of the argument and it’s entirely right that they should make their points,” he said.

“But we should be looking at the opportunities and thinking confidently about the UK and believing what we can do rather than succumbing to a sort of ‘project fear’ mark 2,3,4,5,6.

“There’s a discussion going on, and we haven’t resolved this, but some of the ideas would make it very difficult for us to do meaningful free trade deals.”

Johnson said a model such as the customs partnership would also be a disincentive for countries such as the US in negotiating future free trade agreements. “That’s not what the Americans want to see. What they want to see, like all our friends, is a confident free-trading Britain able to do its own deals,” he said.

“You can’t do that if you remain locked in the lunar pull of Brussels, the tractor beam of Brussels.”