BORIS Johnson will this week undertake his first foreign trip as Prime Minister to deliver an ultimatum to Germany’s Angela Merkel and France’s Emmanuel Macron: scrap the Irish backstop or see Britain leave the EU without a deal on October 31.

A few days later, he will make his first appearance on the global stage when he returns to France to attend the G7 summit of world leaders, set to be dominated from a UK perspective not by more talks with EU leaders but by Mr Johnson’s first meeting as PM before the cameras with Donald Trump.

On Wednesday, Mr Johnson will be in Berlin for his initial encounter with Mrs Merkel, still regarded as the powerbroker behind the EU. A day later, he will be in the French capital for talks with Mr Macron, seen as the most uncompromising of the EU27 leaders when it comes to upholding the exit deal agreed with Theresa May. The PM is also expected to talk to his Irish counterpart, Leo Varadkar, by phone.

No 10 explained it expected there would be "very little discussion" of Brexit during the two foreign visits, predicting that each side would state its position and then move on to other topics.

Instead, it is thought the discussions will revolve around Saturday’s G7 agenda with topics including foreign policy, security, trade and the environment likely to dominate.

German Government sources have suggested that it now accepts that there is a “high probability” the UK will leave the EU without a deal and that it is fully prepared for such a scenario.

For now, both sides, the UK and the EU27, are digging in. Whitehall insiders believe that Brussels will not blink until it realises that MPs will be unable to stop a no-deal Brexit. This, of course, has still to be determined. The parliamentary fog is unlikely to clear before MPs return to Westminster after the recess for the annual party conferences. But, by this time, there will be less than four weeks to go before Brexit Day. A European Council on October 17 could prove decisive one way or the other.

Whitehall sources appear confident that once the penny drops in Brussels, probably within days of the Hallowe’en deadline, the EU27 will move to avoid a no-deal Brexit, not least to spare Ireland a major economic hit. However, nothing is certain. It is thought some Eurocrats want Britain to crash out without a deal as a stark warning to others that leaving the Euro-club is extremely painful and as a means to ensure no other member state contemplates a similar path.

Two days after his meeting with Mr Macron in Paris, Mr Johnson will be in Biarritz for his first face-to-face talks with world leaders.

Brexit is not expected to feature much if at all in the discussions between the G7 heads of government whose main subjects will include staving off a global recession and foreign affairs like Iran, Yemen and Hong Kong as well as tackling climate change.

But Mr Johnson will try to use his first foray on the world stage to talk up post-Brexit Britain, spreading the message about its "renewed global reach".

Media interest, particularly from the UK, will focus on the PM’s first face-to-face meeting with the US President, who has previously praised Mr Johnson.

He has described the PM as “Britain Trump,” saying: “He is tough and smart…He’s going to do a good job.” It has been suggested as a sign of intent, the President will hold his first meeting in Biarritz not with his host, Mr Macron, but with Mr Johnson, hailing before the cameras a new chapter in the so-called Special Relationship.

The PM will be particularly keen to talk up the prospects of a US-UK trade deal once Britain has left the EU.

Last week, Mr Trump predicted a "fantastic" post-Brexit trade agreement, suggesting it was already "moving along rapidly". He has claimed a new deal could be five times bigger than the current one. While fears have been raised that US companies are eyeing up commercial opportunities in Britain’s NHS, Mr Johnson has been adamant the country’s healthcare system is “not for sale”.

Last week during a visit to Downing St, John Bolton, the President’s key aide, made clear Washington was fully behind a no-deal Brexit and that the UK would be “first in line” when it came to a trade deal.

Indeed, US sources have even suggested the Trump administration could sign a general trade agreement with Britain the day after it left the EU on November 1 with more detailed agreements further down the line.

But leading Democrat Nancy Pelosi, Speaker of the US House of Representatives, has claimed a US-UK trade deal would not get through Congress if Brexit undermined the Good Friday Agreement.

One person who will not be at this week’s G7 summit is Jean-Claude Juncker, the outgoing European Commission President. The 64-year-old has had to cut short his summer holiday for an emergency gallbladder operation.