French President Emmanuel Macron was due to arrive in the UK today for the first "socially distanced" No10 summit since coronavirus hit.
The leader will meet Boris Johnson this afternoon for talks on coronavirus and Brexit.
They will also view wartime relics as Macron marks the 80th anniversary of Charles de Gaulle's "Appel" - a BBC broadcast to occupied France following the Nazi invasion in 1940.
But all eyes will be on whether the UK and France can strike an "air bridge" allowing each other's citizens to travel freely between the two nations.
Such an agreement would let the UK suspend its 14-day quarantine policy, which launched on June 8, forcing any new arrivals from France to isolate for two weeks.
Tory MPs and the travel industry are furious at the quarantine plan - under which not a single fine has been issued at the border.
But Foreign Secretary Dominic Raab admitted it could be open to legal challenge if not done properly - or if some nations lose out.
He said: "What we are going to look at is how (international travel) can be done safely and responsibly.
"Of course there is a risk of legal challenge if you open up for one country and not others so we want to make sure we can open up – and this is our starting point – as soon as we can safely and responsibly do so."
He added: "If you open up the airports and don’t open up the Eurotunnel or if you open up to one country but not in relation to others there is always a risk of legal challenge."
PM Boris Johnson's spokesman confirmed the pair would discuss quarantine.
He said: "He said they'd be talking about all sorts of ways in which we can bringing our countries together, making sure we eventually will be able to travel freely to and from each others’ countries."
The Foreign Secretary told BBC Radio 4’s Today programme: “We’ll look at conversations with the French and others about the so-called travel corridors and the exemptions to quarantine that can allow that to be done.”
But those talks will run alongside discussions on the nations' future relationship, wartime history and Covid-19 more generally.
Mr Macron was due to be received by the Prince of Wales and Duchess of Cornwall at Clarence House, before a ceremonial event.
He was due to bestow France's highest order of merit, the Legion d'Honneur, on London.
In Downing Street, Mr Johnson and Mr Macron were due to view artefacts documenting General de Gaulle's time in London and his partnership with Sir Winston Churchill.
They include a Lalique cockerel gifted to Churchill's wife by General de Gaulle and a 1940s microphone the General used to broadcast the Appel.
Gifts from the UK to President Macron include a framed montage of correspondence between Churchill and General de Gaulle, a photo of the pair in Paris after the liberation, and a military replica of Churchill's open top Land Rover Defender.
The two leaders would also watch a flypast of the Red Arrows and their French equivalent, La Patrouille de France, to mark the anniversary of the Appel.
Foreign Secretary Dominic Raab said the Government wants to "open up" the UK when it "safely and responsibly" can, and said ministers are looking "very carefully" at the measure.
He told Sky News: "As we've always said, the quarantine is there to stop the risk of reinfection precisely because we've got Covid down."
Asked why it is in place when UK infection rates are higher than France, he said: "It's not quite as simple as that though, because we've seen in Europe and in Asia, as countries come out of lockdown, the risk of second waves and second spikes.
"But we will look at all the factors very carefully. We want to open up as soon as we safely and responsibly can and we will look at all the mechanisms to do so, and of course we'll have a good conversation with the French.
"I'll be in Berlin tomorrow so we're talking to all of our European partners about these things."