Theresa May’s “endgame” for Brexit talks is keeping the UK tied to the bloc’s Single Market and its rules, and effectively continuing open borders by conceding “freedom of movement by another name”, sources have claimed.

In her Mansion House speech in March, Theresa May spoke of “preserving integrated supply chains” with the European Union (EU) and its market, “a comprehensive system of mutual recognition”, and matching their “regulatory standards”.

Now, speaking to The Guardian, Whitehall sources say that total free movement of goods is “100 percent the direction of travel” for the Government, effectively keeping the UK tied to the Single Market, but with no say in setting its rules.

Brussels has been clear that full access to the market requires open borders, and a cabinet source added that Mrs May could be hoping for a fudge, with the EU allowing “freedom of movement by another name”.

“If you look at how all the negotiations with Brussels have been structured it looks like the whole process has been geared towards this endgame,” they said. “But the big kicker for Brexiters will be freedom of movement.

“What No 10 is banking on is that the EU will let them fudge this and give them some sort of flexibility.

“They’ll come up with clever wording but it will basically be freedom of movement by another name. There’s no way Brussels is going to allow us an opt-out.”

The Whitehall official added: “It is the logical extension of the prime minister’s Mansion House speech that there would be a relatively high degree of alignment… But we want an independent trade policy. It would be a massive negotiating challenge.”

The revelation comes as the Government defeated House of Lords amendments to the Brexit Withdrawal Bill on Wednesday afternoon in the House of Commons, after making promises and concessions to Tory rebels related to giving them a say on the final deal.

“Today’s votes show people in the UK, and to the EU, that the elected representatives in this country are getting on with the job, and delivering on the will of the British people,” Mrs May claimed after the vote.

However, leading pro-Brexit MP Jacob Rees-Mogg said Thursday morning that unless the Prime Minister takes back control of trade policy, Brexiteers could be the ones to block the withdrawal, rather than those who support Brussels.

“Say, for example, the Government comes back with a deal in October saying it will give £39bn to the European Union in return for the good faith of the European Union to discuss a trade deal,” he told BBC Radio 4 Thursday morning.

“That is something that would be very hard to get through Parliament.”