Theresa May's chief Brexit negotiator was overheard telling colleagues in a hotel bar either MPs will back May's deal – or they can expect 'extended talks' with the European Union.
Olly Robbins loudly told his companions on Monday evening Parliament could see a revised deal in March but that 'in the end they (EU) will probably just give us an extension' if it is not backed.
Mr Robbins was overheard by ITV's Angus Walker following the meeting at the UK Ambassador's Residence between Michel Barnier and Brexit Secretary Stephen Barclay.
'The issue is whether Brussels is clear on the terms of extension,' he was overheard saying by Mr Walker.
'In the end they will probably just give us an extension.'
Mr Barclay was said to have held 'constructive' talks last night with the EU's Mr Barnier in Brussels.
After dining on pan-fried North Sea sole with Scottish scallops, the pair agreed to further meetings in the coming days, while their teams will continue to work to find a way forward.
However, Mr Barnier said: 'It's clear from our side that we are not going to reopen the withdrawal agreement but we will continue our discussion in the coming days.'
Mr Robbins, the UK's chief Brexit negotiator had been at the talks and subsequent events, before being at the same hotel as journalist Mr Walker where others in the bar 'did not have to listen hard to hear him'.
Angus Walker wrote for ITV: 'Robbins said that, in his view, he expects the choice for MPs to be either backing May's deal or extending talks with the EU.
Chief negotiator Olly Robbins was overheard talking in a bar about Mrs May and Brexit
'He expects MPs in March to be presented with backing a reworked Brexit deal or a potentially significant delay to Brexit, he told colleagues last night.
'This is significant. The prime minister has consistently said that we are leaving the EU on March 29th and that she will not engage with discussion about delaying our departure.
'We now know her chief negotiator – who works directly for her – appears to be expecting a delay. A delay which she has always said was an option that was not on the table.
'Robbins added that he thought the fear of a long extension to Article 50 might focus MPs' minds.'
Theresa May has always denied she wants to remain in a Customs Union with the EU.
Olly Robbins has the inside track on Britain's Brexit plans
But comments made by Mr Robbins suggest that may have been the original plan.
Mr Walker wrote: 'What is also striking is how Robbins confirmed that the original plan was for the backstop, which would keep the UK in the customs union, was designed not as a 'safety net' for the island of Ireland but as 'a bridge' to the long-term trading relationship - which is something the prime minister has always denied.'
He also overheard Mr Robbins saying: 'The big clash all along is the 'safety net. We agreed a bridge but it came out as a 'safety net'.'
It was also suggested Mr Robbins and the Prime Minister will seek to have the Withdrawal Agreement amended so that the Good Friday Agreement would be less of an obstacle' on the backstop
To do that they will attempt to have the European Commission 'agree that the word 'necessary' in the Northern Ireland protocol is defined as 'necessary subject to the future trade deal'.'
Mrs May is running short on time.
More than a dozen ministers could join the revolt at the showdown on February 27 as pro-EU MPs told MailOnline the votes will finally be the crunch moment for no deal.
Earlier, the PM urged MPs to 'hold their nerve' as she appealed for 'a little more time' to get concessions on the Irish border backstop in bitter Commons clashes.
However, EU chief negotiator Mr Barnier emerged from the dinner with Brexit Secretary Steve Barclay in Brussels last night to insist the Withdrawal Agreement will not be renegotiated.
The Tory leader tried to quell a mounting rebellion