The King made history as he became the first British royal to speak from the French senate, while Queen Camilla had a giggle as she played table tennis with First Lady Brigitte Macron on day two of their state visit to France.
Charles, 74, pledged to do whatever he can to strengthen the "indispensable relationship" between the UK and France in a historic address to the nation's senate.
In a speech delivered in both French and English, the King spoke of the "friendship and warm familiarity" between the two countries, as well as the unity on issues such as climate change and foreign military aggression. Watch some of his speech in the clip below...
He said: "For the time that is granted to me as King, I pledge to do whatever I can to strengthen the indispensable relationship between the United Kingdom and France – and, today, I invite you to join me in this endeavour. Together, our potential is limitless.
"Let us, therefore, cherish and nurture our entente cordiale. Let us renew it for future generations so that, I would like to propose, it also becomes an entente pour la durabilite (agreement for sustainability) – in order to tackle the global climate and biodiversity emergency more effectively.
"A commitment to each other, and to the values we so proudly share; a commitment inspired by the example of the past, and emboldened to grapple with the immense challenges in the world around us.
"As neighbours, friends, partners and allies, there is no challenge to which we cannot rise, as we have done so often in the past. Let us stride forward with hope and courage – and let us do so together."
The King opened his speech in French, saying: "I need hardly say how greatly honoured I am to have been invited by the Presidents of both Houses to speak here, in this hallowed chamber, which has been the upper house of French politics in one form or another since 1799."
Charles told senators: "Quite simply, the United Kingdom will always be one of France’s closest allies and best friends."
It comes the day after President Emmanuel Macron and First Lady Brigitte Macron welcomed Charles and Camilla to the French capital, with a ceremony at the Arc de Triomphe, an audience at the Elysee Palace and a glittering state banquet at the Palace of Versailles.
Meanwhile, Queen Camilla and Brigitte Macron, the wife of French President Emmanuel Macron, launched a new Franco-British literary prize at the Bibliotheque Nationale de France.
Dressed in a white coat coat and a monochrome dress, Camilla, 76, delivered a speech in "rusty French," saying: "I very much hope that this Prize will go a long way to proving that Victor Hugo was unfair to us when he said, 'L’Angleterre a deux livres', 'England has two books' – as dearly as we value the Bible and Shakespeare, I promise that we have many more than two, as the esteemed authors gathered here demonstrate… And, just as in France, our writers every year create new masterpieces which this Prize aims to celebrate.
"Brigitte Macron and I share a deep love of literature and a passion to promote literacy: through our respective work, we have seen first-hand the life-changing power of books to bring us joy, comfort, companionship, laughter and tears, opening our eyes to others’ experiences and reminding us that we are not alone.
"To quote Victor Hugo once again, 'Apprendre à lire, c'est allumer du feu ; toute syllabeépelée étincelle', 'To learn to read is to light a fire; every syllable that is spelled out is a spark.'"
The King and Queen also joined Mrs Macron at the Rugby World Cup village in Saint-Denis, northern Paris, where Camilla put her table tennis skills to the test.
Charles laughed as his wife practised hitting the ball before the Queen challenged Mrs Macron to a game.
The wife of Emmanuel Macron appeared to get the better of Camilla as they played for a few minutes in a well-spirited match.
The Queen hit the ball into the net several times and joked with Mrs Macron about the game. See the moment in the clip below...
Charles chatted with Bamba and Welsh rugby player Dan Biggar, who said the King’s visit has given France a lift.
Bamba added: “Everyone in France is enjoying the World Cup at the minute, so it’s great to have this visit now.”
Their Majesties were then given the opportunity to try out their crafting skills as they toured Le 19M Campus to learn about the organisation’s work to promote education, creativity and inclusion through teaching young people traditional ‘haute couture’ skills such as embroidery, pinning and producing tweed.
After their visit to the Le 19M Campus, the King and Queen went to a Paris flower market named after the late Queen.
The pair greeted two stallholders, including Lionel Vivani, who has had a stall for 25 years. Mr Vivani told the King how he showed his mother around the market.
Afterwards, Mr Vivani said: "It was an honour to meet the King. I have fond memories of meeting the Queen nearly ten years ago and I'm glad I am still here for this visit."
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