French President Emmanuel Macron will hold his first summit with British Prime Minister Theresa May today in London.
While ties between the two neighbouring countries remain close, new tensions are evident in the wake of Britain's decision to leave the European Union.
Military and security matters have always featured prominently. Both Britain and France enjoy unique advantages - they account for Europe's largest standing armed forces, possess the continent's only nuclear arsenals, and occupy permanent seats on the United Nations Security Council. In 2010, the two nations concluded a unique 50-year military cooperation treaty, and some of the provisions remain a secret, particularly those that relate to the joint development and testing of nuclear weapons.
Now, with defence budgets stretched on both sides, French and British leaders have a vested interest in continuing to expand defence cooperation. And their intelligence agencies, facing the same threat of terrorism, have never worked in closer fashion.
Still, even in the security field, tensions are creeping in. Mr Macron has not hidden his irritation at what he sees as British indifference to French stability efforts in Africa. A large contingent of French troops have been deployed in Mali to prevent the African state's collapse, and Mr Macron's appeal to Europe to shoulder the burden has largely fallen on deaf ears in London.
The French also want the British to commit to a newly created EU force which could be deployed quickly to zones of conflict. The British are hesitant, partly because they feel it could overshadow Nato, the United States-led military alliance in Europe, and partly because Mrs May would face a backlash from opponents of the EU inside her government, who hope that once Britain leaves the EU, it will not saddle itself with any new European obligations.
There are also wider areas of discord. Mr Macron wants Britain to accept more asylum seekers from Third World nations, who are stranded in France on their way to Britain. On Tuesday, he ostentatiously visited a migrant camp in Calais, the French port city facing the channel that separates the two nations.
Mr Macron came to power last year vowing to tear up a 2003 deal under which Britain gained the right to conduct immigration checks on French soil, to prevent the entry of illegal immigrants. Since then, he has accepted that the pact could continue, but is keen to disperse the refugee holding camps on the French side of the border. "Calais is a land of passage, which has become a dead end for thousands of women and men who have spent years on the road", he said during his tour of the city.
Mrs May, who initially resisted even putting immigration on the agenda for the summit, may be able to offer more cash, on top of the €80 million (S$129 million) the British already pay yearly for handling asylum seekers in France. But she is in no position to accept large numbers of immigrants. Beyond that, both leaders know that their biggest political haggling in decades is only just about to unfold - over the future relationship Britain will have with the EU.
Mrs May hopes to leverage her country's continued military importance - and the fact that trade between the two neighbours now stands at around $132 billion a year - against French support for a better trade deal to govern relations between the EU and Britain after Brexit next year.
But Mr Macron is in no hurry to offer concessions, partly because it suits France to continue exercising influence from within the EU, rather than outside it. The French also believe that Britain now needs them more than they need the British.
Either way, Mr Macron and Mrs May are in no mood for the pomp and ceremony that traditionally accompanies summits. Their meeting takes place in the spartan and more secluded rural grounds of the Sandhurst Military Academy.