In Paris, His Majesty spoke of the “unprovoked aggression” on our continent and the “resolute solidarity” in which both the UK and France stood with Ukraine. He added: “Just as we stand together against military aggression, so must we strive together to protect the world from our most existential challenge of all – that of global warming, climate change and the catastrophic destruction of nature.”

The challenge is “both great and grave”, he said, but added that it was “increasingly heartening to see the action that is being taken by our governments, our people and, more and more, by the private sector”. 

In 2021, Charles launched the Terra Carta, or Earth Charter – a 10-year “recovery plan” for the private sector –that was considered his biggest environmental initiative.

Among the guests at a state banquet held at the Palace of Versailles on Wednesday evening was Brian Moynihan, director general of Bank of America, one of its leading supporters.

As he hailed the “entente cordiale”, Charles urged the assembled politicians and dignitaries not only to “cherish and nurture” the landmark 1904 treaty but to build upon it with more action to protect the planet.

Today, he said, the bond was in their collective hands, having been “passed with pride from father to daughter, mother to son, just as it has been handed through the generations of my own family”. 

He added: “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 Durabilité – in order to tackle the global climate and biodiversity emergency more effectively.”

The King was given a second standing ovation, as he concluded with the words: “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.”