Over the following months, the two leaders regularly exchanged messages over WhatsApp, sharing private jokes and infuriating officials who wanted all communication done through proper channels.

“On a personal, individual level, they get on fine,” says Adam Plowright, author of the Macron biography The French Exception. “There are lots of things they have in common; they both see themselves as intellectuals, they love history and literature. There is a connection on that level.

“I think they also respect each other for what they have achieved – Johnson recognises Macron’s political talent in founding his own movement [En Marche!] and getting elected, while Macron respects Johnson’s ability to connect with people and as a serial winner.”

Macron even borrowed from Johnson when he visited London during his presidential campaign in 2017, telling an audience of French expatriates that London was France’s sixth-biggest city, repeating a phrase coined by Johnson when he was the city’s mayor to describe the huge number of French citizens living in the capital.

Championing distinctly Johnsonian principles, he also praised the entrepreneurial, risk-taking attitudes that had attracted much of his audience to Britain.

Nor is Johnson a natural Francophobe. He enjoys speaking French, having lived in Brussels for part of his life, and was an admirer of the former European Commission president Jacques Delors whom he regarded as a shoulder-to-the-wheel leader who got things done. Those who have worked with the Prime Minister say he is a fan of cross-channel collaboration, such as the Channel Tunnel and Concord.

The odds against the purported Macron-Johnson “bromance” remaining intact were always long, however.