THE Prime Minister faces open revolt from her hardline Brexiteer cabinet colleagues after reports emerged that she’s likely to perform a thumping great u-turn and keep Britain in the EU’s customs union.

One report in the press yesterday even suggested May’s officials had “wargamed” what could happen after the climbdown, and was relaxed that the worst possible outcome would be Boris Johnson resigning.

Though other reports suggested he’d remain rather than leave.

It’s become increasingly clear over the last two years that it is impossible for the UK to leave the customs union, the arrangement which allows goods to cross European borders without time-consuming customs checks or paying any tariffs, without a hard border in Northern Ireland.

Brexiteers hate the agreement as it means the UK has to charge the same tariffs on outside countries as the rest of the EU, so there would be a competitive advantage.

The government has repeatedly said it would have technological fixes for Ireland, allowing a frictionless border despite different standards and rules on goods.

There have been doubts from Brussels on how that would work, and Whitehall has yet to provide convincing answers.

May faces debates and votes on the customs union in the House of Commons on Wednesday and Thursday, though they will be advisory rather than binding.

However, last week, the Lords voted to stay in a customs union. And the only way that can be undone is through a vote in the Commons.

It’s not clear if May would have a majority to achieve that.

According to the Sunday Times, one of the Downing Street political team told a meeting of officials on March 20 that May and senior aides “will not be crying into our beer” if parliament forces the government’s hand.

The Number 10 officials, according to the Times, predicted Michael Gove and David Davis would accept remaining in the customs union and Johnson and Liam Fox would be likely to quit – both have been very public in their opposition.

A source familiar with the discussion told the paper: “The discussion focused on what to do if parliament votes to stay in a customs union. Someone from the political unit at No 10 said: ‘We wouldn’t cry into our beer if we were forced to do this.’ The PM needs to go through the choreography of trying to leave but we might be forced to do it.”

Though it may anger some of the more fervent Brexiteers in the party, there was support for May from Stephen Kerr, one of the Scottish Tory MPs. The Stirling politician is on the hard-Brexit wing of the party, having signed up to the European Research Group, the eurosceptic bloc of parliamentarians led by Jacob Rees-Mogg.

Speaking on yesterday’s BBC Sunday Politics Scotland, he suggested any u-turn would be perfectly compatible with what the Prime Minister had promised.

“Well let’s be absolutely clear about what the government’s position is: leaving the European Union means that we leave the customs union and single market,” he said.

Kerr added that the UK needed “to negotiate a trade agreement, a free trade agreement, with with the EU and that should involve tariff free trade and so there needs to be some kind of customs agreement”.

The MP added: “Britain wants to be post-Brexit, a champion of free trade and we want to have a trade agreement, including dealing with issues around tariffs both the monetary tariffs and also the non-tariff barriers that can sometimes impede free trade.”

In February, Kerr was a signatory to an ERG letter calling for “full regulatory autonomy” insisting the the UK should not be a “rule taker without any substantive say in whatever Brussels decides.”

His erstwhile leader, Rees-Mogg, yesterday told the Sunday Telegraph: “Trying to keep us in a customs union would be deeply divisive in the party, the Commons and the country at large,”

Former Brexit minister David Jones also criticised the idea, writing that it was “a Byzantine scheme designed first to slow down Brexit and then to strangle it”.