The parliamentary vote on the Brexit deal could force Theresa May into further renegotiations with Brussels or face the prospect of crashing out of the EU and on to painful World Trade Organisation tariffs, according to Labour’s Shadow Brexit Secretary Keir Starmer.

Last night Labour called the decision to allow a vote on the deal “a major concession” even as No 10 denied that any concession had been given.

But Mr Starmer told the Today programme that in reality, the prospect of Parliament voting against Ms May’s deal would force her into further negotiations, rather than leaving the EU with no free trade arrangements in place.

“The idea the prime minister would seriously say in 2019: ‘Well, rather than go back and see if I can improve and satisfy Parliament I will simply crash out’ that would be a reckless act,” he told BBC Radio 4’s Today programme.

Parliament will tonight vote on the final amendments to the Brexit bill. Mr Starmer said his party was largely satisfied with the concessions the Government had made. ”It wasn’t everything we wanted but it was new,” he said.

Angela Eagle, the former leadership contender, had called the deal a “Hobson’s choice”, in that MPs would either have to accept the terms of Ms May’s negotiation or leave with nothing.

But Mr Starmer said the prospect of Ms May returning with a deal that would not satisfy Parliament was unlikely, and that it would be a “very serious situation” for the prime minister to be in.