Rishi Sunak and Emmanuel Macron’s “Le Bromance” relationship saw them hold a one-to-one meeting of more than an hour at an Anglo-French summit in Paris on Friday.
The length of the get-together in the Elysee Palace took officials by surprise as it was planned to be shorter.
Only at the end did they call their respective chiefs of staff in for the meeting.
No translators were present at the meeting which was conducted in English.
They exchanged rugby shirts signed by the England and French teams due to play each other in “Le Crunch” clash at Twickenham on Saturday.
The two then met business leaders and a “family photo” of the PM, president and ministers from both countries was taken.
They then lunched on vegetarian sushi, turbot, artichoke and a praline tarte.
A spokesman told reporters the meeting was “warm and productive”.
“They discussed the upcoming Six Nations match, having exchanged signed shirts.
“They both agreed on the need for further collaboration on a range of issues, including on defence, energy security and illegal migration.”
During a press conference later on Friday, the pair embraced after Mr Sunak told the French president he felt “very fortunate to be serving alongside you”.
Mr Sunak described his counterpart as a “friend of Britain” as he thanked him for his “graciousness” towards the country after the Queen’s death last year.
“I’ve learned very quickly in this job that there are some things you can control and some things you can’t. And one thing you can’t control is who you get as an international counterpart,” Mr Sunak said.
“I feel very fortunate to be serving alongside you and incredibly excited about the future we can build together. Merci, mon ami.”
The pair then shook hands and embraced.
During Liz Truss’s brief time as prime minister, she said the “jury is out” on whether Mr Macron was a “friend or foe”.
But her successor has struck a very different tone since taking office in October.
Mr Sunak, speaking later at the Elysee Palace briefing, said he wanted to usher in a “new chapter” in Anglo-French relations.
The Vote Leave campaigner made the comments after the French leader spoke about the need to “fix” issues that had been created by Britain’s exit from the European Union.
The Conservative Party leader said: “I always say, we left the EU but we didn’t leave Europe. Emmanuel said previously ‘Brexit didn’t change geography’.
“We want to have a close, co-operative, collaborative relationship with our European partners and allies.
“And of course, that starts with our nearest neighbour, France, and today is the first step on that journey.
“We’re writing a new chapter in this relationship, and I’m really looking forward to everything that we can build on in the coming months and years ahead.”
