Notre Dame and La Poste are the latest targets the French purists’ ire. They have cited as the most egregious case “Ma French Bank”, the online bank recently opened by La Poste.

One of the cases concerns the reconstruction of Notre Dame in Paris – which is accused of failing to carry two foreign languages on its signs, in breach of a 1994 law that requires translation on public signs to be in two foreign languages. The purpose of the law was to avoid giving precedence to English.

President Macron, who was formerly an investment banker in London, is known to switch to English, even in the Élysée Palace. President Chirac, in contrast, once walked out of a Brussels summit when he was addressed in English.

French, which has given so many words to English, has been importing them since the end of the Second World War, propelled by technology, business and pop culture.

“The massive, unstable influx is damaging the identity of our language and in the long term its future,” the Académie française said last year.

The campaigners want offending bodies to be fined for falling foul of the “Toubon” language law of 1994 and are taking institutions to task.

Ma French Bank said it was promoting France internationally with the slogans “made in France” and “le French touch”, which “mix French and a dash of English while staying accessible”.