Buckingham Palace will be guarded by French troops on Monday following King Charles' approval to honour 120 years of friendly relations between England and France.
The event is a historical first, and will mark the anniversary of an agreement known as the Entente Cordiale, translated as 'cordial agreement'. The agreement was put in place in April 1904 in a bid to resolve long-standing disputes, creating a diplomatic understanding between the two countries.
In celebration of its anniversary, 32 members of the Gendarmerie’s Garde Republicaine will join 40 soldiers from the Scots Guards for a parade.
While the Gendarmerie will guard the palace's forecourt, they will not take the place of their British counterparts in guarding the King. This responsibility is only afforded to members of the British Armed Forces and Commonwealth troops.
The Gendarmerie will be marched on and off the Buckingham Palace forecourt by the Band of the Grenadier Guards, who will also perform both countries' national anthems and a programme of Anglo-French music
Squadron Chief Guillaume Dewilde, who is leading the French detachment during the Changing of the Guard, said: "I am extremely proud to have been asked to share this moment with our British friends.
"We are like siblings, and to celebrate this moment together is a symbol of the strength of the relationship between our two countries.!
Garrison Sgt Maj Andrew Stokes, who has been responsible for delivering all ceremonial training, added: "It is crucial for everyone in Nato to have a strong relationship.
"And this is an opportunity to both celebrate the 120th anniversary of the signing of the Entente Cordiale and also demonstrate our close relations with the French.
"Our first rehearsal went really well so we're not nervous at all. It will be a wonderful celebration and an opportunity for the public to witness such a spectacle."
Over in the French capital, a similar ceremony will be attended by President Macron and will be held in Paris earlier that day.
British guards will join their French counterparts to guard the French Presidential Residence, the Elysee Palace. This will be the first-ever example of a foreign state guarding the French Presidential Residence.