DMcG, here is the whole piece,

Theresa May’s team has privately admitted she may have to accept permanent membership of a European customs union, after a secret wargaming exercise concluded that even Brexiteers such as Michael Gove and David Davis would not resign in protest.
The prime minister has insisted that the UK will leave the common tariff area so it can pursue free trade deals outside the EU. But one of May’s political team told a meeting on March 20 that she and senior aides “will not be crying into our beer” if parliament forces the government’s hand — a position that will enrage some Brexiteers.

The Lords voted last week to stay in a customs union and 10 Tory MPs are expected to do so in the Commons, overturning May’s majority.
In the crunch meeting — attended by Oliver Robbins, May’s chief Brexit negotiator — officials predicted Gove and Davis would accept that outcome while only Boris Johnson and Liam Fox would be likely to quit. The foreign secretary has publicly said staying in a customs union would be “worse” than remaining in the EU.
Gove’s stance was confirmed by four sources who have discussed the issue with the environment secretary. “Michael is not ready to roll over in cabinet,” one said, “but he recognises that the arithmetic is difficult.”

The revelations will be greeted with anger by hardline Brexiteers around Jacob Rees-Mogg, who have privately warned Tory whips that remaining in a customs union would prompt a leadership challenge.
A source familiar with the discussion said: “They sat in a room in 9 Downing Street when they were discussing Brexit and Olly Robbins came in. 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.”
Robbins has been pushing for customs union membership as a way of preventing a hard border between Northern Ireland and the Republic. The source added: “The civil service fast stream have a pool on who is going to resign first. All the money is on Liam Fox and then Boris.”
Members of May’s Brexit war cabinet will meet on Wednesday to discuss trade before finalising the UK’s stance ahead of a crunch EU summit on June 29.
In an effort to turn the screws, Labour is demanding the prime minister bring forward a binding Commons vote on whether Britain should remain in the union.
In a letter to May, Sir Keir Starmer, Labour’s Brexit spokesman, claims that delaying the vote has already led to “deep anxiety” for businesses and communities across the UK, particularly in Northern Ireland. He offered to surrender Wednesday’s opposition day debate so she can bring forward the vote.
“The government cannot indefinitely delay the passage of legislation through the Commons for fear of defeat on crucial votes,” Starmer writes. “If a decision is not made until June then that will leave just three months to negotiate the details of the final agreement.”
A Downing Street source said May would continue to argue for Britain to quit the union. “Government policy is to leave the customs union. That’s what we will continue to argue for. That’s where we want to end up.”