The King will stress the vital partnership between France and the UK in the face of a “multitude of complex threats” at the state banquet in honour of French President Emmanuel Macron, declaring “as friends and as allies, we face them together”.
Charles and the Queen are set to welcome the French leader and his wife Brigitte to Windsor Castle on Tuesday as Mr Macron begins his three-day state visit to the UK.
At a glittering banquet in the historic Berkshire landmark in the evening, the monarch will deliver a speech, highlighting how “these challenges know no borders: no fortress can protect us against them this time”.
But he will tell Mr Macron that Britain and France can help lead the way in confronting threats relating to defence, technology and climate change, saying: “Our two nations share not only values, but also the tireless determination to act on them in the world.”
Charles and Camilla are hosting Mr Macron and the first lady at the historic royal residence.
They will be feted with a carriage ride through the town, a ceremonial welcome and the opulent state dinner.
The King, in his toast, will reflect on 1,000 years of “shared history and culture between our two peoples”, including many of the royal family’s personal connections to France.
“For centuries our citizens have admired each other, amused each other, and imitated each other”, he will say, and reveal how he remains “in awe of France’s extraordinary attributes and achievements”.
Charles will also hail the Anglo-French partnership as vital amid the many challenges of today, saying: “Our two countries face a multitude of complex threats, emanating from multiple directions.
“As friends and as allies, we face them together.”
It marks the first state visit to the UK by an EU head of state since Brexit, and will see Mr Macron address parliamentarians in the Palace of Westminster’s Royal Gallery and, on Thursday, join a UK-France Summit at Downing Street.
Top of the agenda for that summit is likely to be action on small boat crossings as Sir Keir attempts to solve one of voters’ key issues.
This could include a so-called “one in, one out” deal to exchange Channel migrants for asylum seekers in Europe who have a link to the UK.
Such an agreement is thought still to be on the table, but a deal has not yet been done.
Ministers have also been pushing for France to revise its rules to allow police to intervene when boats are in shallow water, rather than requiring them still to be on land.
Last week, French authorities appeared to change tactics when officers used a knife to puncture an inflatable boat after it had launched.
But on Monday, Downing Street appeared to suggest a new approach had been discussed but not yet rolled out.
A spokesman for Number 10 said: "We are the first Government to have secured agreement from the French to review their maritime tactics so their border enforcement teams can intervene in shallow waters.
"This is operationally and legally complex, but we're working closely with the French. We expect this to be operationalised soon."
Mr Macron's state visit comes a week after the total number of people crossing the Channel in small boats this year passed 20,000.
The total now stands at 21,117, according to PA news agency analysis of Home Office figures, and is a record for this point in the year.
The Prince and Princess of Wales will play a role in the state visit by meeting the president and the French first lady at RAF Northolt on Tuesday morning on behalf of the King and travelling with them to Windsor.
Charles and Camilla will formally greet their guests on a Royal Dais constructed on Datchet Road in Windsor town centre, with the castle in the backdrop as gun salutes sound in nearby Home Park.
The King, the Queen, the Waleses and Mr and Mrs Macron will then take a carriage procession through Windsor and along part of the Long Walk which leads to the castle, just as former French president Nicolas Sarkozy did in 2008.
Mr Macron’s state visit to the UK, from July 8-10, is the first to be hosted at Windsor Castle, rather than Buckingham Palace, in a more than a decade since that of the Irish president Michael D Higgins in 2014.
State visits, which capitalise on the royals’ soft power to strengthen diplomatic ties overseas, will be hosted at Windsor for the next few years while reservicing work continues at the London Palace and starts to affect the state rooms.
The last state visit to the UK from France was in March 2008 when the now-disgraced Mr Sarkozy, since convicted of corruption and influence peddling, and his wife Carla Bruni, were the guests of Elizabeth II at Windsor.
The arrangements are likely to form the template for US President Donald Trump’s high-profile state visit in September, but much will depend on security considerations for the US leader, who survived an assassination attempt last year.
A ceremonial welcome will be staged in the castle’s quadrangle with Camilla, William, Kate and Mrs Macron watching as the King and Mr Macron inspect the Guard of Honour.
Lunch will be hosted in the State Dining Room, after which the president and his wife, the King and Queen and members of the royal family will view a special exhibition of items relating to France from the Royal Collection in the Green Drawing Room.Mr and Mrs Macron will also travel to London on Tuesday afternoon to see the Grave of the Unknown Warrior at Westminster Abbey and visit the Palace of Westminster where the French leader will address parliamentarians before meeting opposition leaders at Lancaster House.
The King and president will both deliver speeches at the banquet in the medieval St George’s Hall, where some 160 guests will be seated at the elaborately decorated 50 metre table, which will run the full length of the vast room.
Kensington Palace has yet to confirm whether Kate will attend the banquet.
The princess opened up about her “rollercoaster” cancer recovery, its life-changing impact and putting on a “brave face” last week.
The King and Queen paid a state visit to France in September 2023 and enjoy a warm rapport with Mr and Mrs Macron, who will stay in the castle during their trip.
Mrs Macron, 72, sparked a storm in May when she was seen pushing her husband’s face away with both hands before they disembarked a plane in Vietnam.
The 47-year-old president dismissed the gesture – caught on camera – as horseplay, but it caused a stir in France, with daily Le Parisien newspaper asking: “Slap or ‘squabble’?”
The couple, married since 2007, met at the high school where Mr Macron was a student and Brigitte was a married teacher.
The visit comes a year after the UK and France celebrated 120 years since the signing of the Entente Cordiale.
The Anglo-French agreements in 1904 ushered in improved relations between the two countries which had fought against each other during the Napoleonic Wars.
