Boris Johnson has said he is “cautious” about progress in Brexit talks as he met with European Commission president Jean-Claude Juncker for their first face-to-face discussions since he became Prime Minister.

The PM was set to personally warn Mr Juncker during a working lunch in Luxembourg on Monday morning that he would not delay the UK’s departure from the EU any further – “no ifs, no buts”.

But, with the Halloween deadline looming, Mr Johnson needs to secure a new Withdrawal Agreement that would be approved by MPs shortly after next month’s EU summit.

If not, he faces being forced to ask for a delay to Article 50 to the end of January after Parliament approved a law designed to prevent no-deal.

However, Mr Johnson has suggested he could ignore the legislation to fulfil his “do or die” pledge to get the UK out of the bloc by October 31.

The PM was asked why he was so optimistic about the talks.

“Well, we’re cautious – cautious,” he told reporters, as he was flanked by the EU’s chief.

Mr Juncker was earlier asked if he was confident of progress. “We will see,” he replied.

The UK’s permanent representative to the EU, Sir Tim Barrow, and the EU’s chief negotiator, Michel Barnier, also entered Luxembourg City’s Le Bouquet Garni restaurant.

Snails, salmon and cheese were said to be on the menu – and Mr Juncker told reporters he was paying.

Boris Johnson and Jean-Claude Juncker
Boris Johnson said he was ‘cautious’ of Brexit progress after meeting Mr Juncker (Stefan Rousseau/PA)

Brexit Secretary Stephen Barclay and Number 10 negotiator David Frost were also expected to travel to Luxembourg, where Mr Juncker was prime minister for 18 years.

It was their first meeting since Mr Johnson became PM in July, though they have spoken on the phone.

Writing in the Daily Telegraph ahead of the meeting, Mr Johnson said he was working “flat out” for an agreement but that he would force through Brexit even if a deal cannot be reached at the European Council summit next month.

“But be in no doubt that if we cannot get a deal – the right deal for both sides – then the UK will come out anyway,” he added.

A Downing Street source said any further delay would be a “huge mistake” which would pile on “additional long months of rancour and division”.

“This is why the PM will stress to Mr Juncker that, while he wants to secure a deal, if no deal can be agreed by October 18 his policy is to leave without a deal on October 31 – and reject any delay offered by the EU,” the source said.

(PA Graphics)
(PA Graphics)

The Benn Act passed by Parliament after MPs seized control of Commons business requires the PM to seek an extension to the Brexit process if a deal has not been reached by October 19.

Foreign Secretary Dominic Raab suggested the Government was still examining the implications of the legislation.

“The UK Government is always going to behave lawfully,” he told BBC Radio 4’s Today.

“At the same time, the legislation that was required, the surrender bill, is deeply, deeply flawed.”

Downing Street has sought to downplay speculation that Monday’s meeting would be a breakthrough moment and Mr Barclay said on Sunday that while there was still “significant work” to do to reach an agreement, a “landing zone” for a deal was in sight.

With Mr Johnson needing to break the deadlock in Parliament, he must find an alternative to the Irish backstop, which aims to prevent a hard border returning to the island of Ireland.

There have been suggestions that the PM is planning an alternative that would keep Northern Ireland more closely aligned with the EU than the rest of the UK.

Mr Juncker, in an interview on German radio, said “time is running out” for an alternative, as he suggested no-deal was unpatriotic.

“If you love your country – and I assume there are still patriots in the UK – you do not want to wish your country such a fate,” he said.

Mr Johnson was due to meet the Luxembourg’s current prime minister, Xavier Bettel, for further talks in the afternoon.