Nicola Sturgeon has warned Jeremy Corbyn not to fall into a Tory “trap” and sell out a soft Brexit too cheaply as two of Theresa May's most senior ministers made clear they are now willing to accept a customs union to secure an orderly EU withdrawal.

The First Minister, after separate meetings with both the Prime Minister and the Labour leader, told reporters: “If I were in Jeremy Corbyn’s shoes right now I would be very wary about signing up to anything that may not be able to be delivered,” warning that any Con-Lab deal “could be unpicked by a prime minister who is not Theresa May but perhaps Boris Johnson”.

To heckling from pro and anti-Brexit demonstrators outside Westminster and cries of “traitor,” Ms Sturgeon said: “He should be wary about not falling into a trap either selling the votes of his party too cheaply or taking things on trust from the PM…He should be insisting that whatever compromise he reaches in this place it goes back to the people.”

The Herald:

She said she was “not overly optimistic” that Labour would support a second referendum but warned Mr Corbyn’s party would “pay a heavy price if they do a sort of tawdry second-best deal with the Tories” and became the “hand-maidens of a Tory Brexit” without giving the public a say.

Her words came as Labour tensions over a second referendum spilled out after Emily Thornberry, the Shadow Foreign Secretary, argued that any deal had to be put to a public vote.

She told colleagues in a note: “If we look like reaching any other decision than a confirmatory vote that would be in breach of the decision made unanimously by conference in Liverpool and overwhelmingly supported by our members and it needs to be put to a vote‎ by the Shadow Cabinet.”

Earlier, the Labour leader and Mrs May held a 90-minute meeting in the Commons, which the former said was “useful but inconclusive” and the latter “constructive”.

They announced further talks would take place today between their respective teams.

The series of Brexit meetings came as drama unfolded in the Commons chamber.

In a highly unusual move, John Bercow, the Speaker, cast his vote in favour of the Government position, according to convention, after a vote to facilitate a third round of so-called “indicative votes” on Brexit alternatives, set for Monday, was tied 310 votes to 310 votes.

Minutes later, a vote to introduce a Bill, put forward by Labour’s Yvette Cooper, to prevent a no-deal outcome from taking place was won by just one vote.

While the FM described her meeting with Mrs May as “good, positive and friendly,” she admitted she had “no sense of where the PM’s boundaries were” in relation to Brexit.

However, David Mundell insisted Mrs May was prepared to be “flexible,” noting how the public was fed up by the Brexit stalemate.

The Scottish Secretary, stressing how a customs union was not his preferred choice, nonetheless said: “It’s very important now we find the basis for leaving, that can command majority support. Therefore, I would be willing to accept leaving on the basis of a customs union if we can achieve an orderly exit, if we can get a stable majority in Parliament and ratification for our agreement.”

In what might be the first indication Mrs May could be prepared to move towards the customs union option - something she has previously argued against because it would preclude the UK from having its own trade deals – Mr Mundell’s opinion was echoed by Geoffrey Cox.

The Attorney General said a customs union was "not desirable" but if that was the only way of leaving the EU, then he would take it.

However, the Government’s senior legal adviser also pointed out that once the UK left the Brussels bloc, it could “in some considerable years’ time” also exit a customs union.

"There's nothing to stop us removing ourselves from that arrangement, so we can't look at these things as permanent straitjackets upon this country," he explained.

If the May-Corbyn talks come to nought, then it is possible MPs will be faced with a run-off vote between Mrs May’s three times-rejected plan and other options such as a customs union.

The PM has said she wants the result of a run-off to be binding and which can be taken to next Wednesday’s EU summit to help ensure Britain can leave the Brussels bloc in an orderly way without the country having to take part in the forthcoming European parliamentary elections.