French-British Guard Exchange

French and British troops will swap roles to take part in the changing of the guards ceremonies outside the palaces of the other country's head of state, in an unprecedented move to celebrate 120 years since the Entente Cordiale.

Signed in 1904, the Entente Cordiale accord cemented an improvement in relations after the Napoleonic Wars and is seen as the foundation of the two NATO members' alliance to this day.

"Britain and France, two founding members and Europe's nuclear powers, have a responsibility in driving the alliance to deal with the challenges before it," the diplomats wrote in The Telegraph.

"We must do even more to ensure we defeat Russia. The world is watching and will judge us if we fail."

The ceremonies will see British guards take part in the changing of the guard outside the Elysee Palace of President Emmanuel Macron, and his French guards do the same outside Buckingham Palace in London of King Charles III.

"This is the first time in the history of the Elysee that foreign troops have been invited to participate in this military ritual," a French presidential official said.

It will be watched by the Duke and Duchess of Edinburgh -- Prince Edward and his wife Sophie -- accompanied by the UK chief of the general staff, General Patrick Sanders, and French chief of the army staff Pierre Schill.

The event on the forecourt of Buckingham Palace will mark the first time a country from outside the Commonwealth -- which mostly includes English-speaking former British colonies and possessions -- has taken part in the changing of the guard.

The signing of the Entente Cordiale on April 8, 1904, is widely seen as preparing the way for France and Britain joining forces against Germany in World War I.

While the accord is often used as shorthand to describe the Franco-British relationship, ties have been bedeviled by tensions in recent years particularly after Brexit.

But a state visit by King Charles last autumn was widely seen as a resounding success that showed the fundamental strength of the relationship.