The expression filer à l'anglaise stands as an obvious testimony to the everlasting squabble between France and England throughout history. It is the French version of to take French leave (or French exit) in English. In both languages, the expression means leaving a place or sneaking out of a party without saying goodbye to anyone. And it's not considered a polite thing to do, tempting as it might to just slip away and avoid taking formal leave of every single person around the dinner table. There is a slight difference between the English and the French idioms, however: The English French leave often refers to cowardice while the French expresses the idea of sneaking out like a thief. Another French expression to signify this kind of behavior is in fact partir comme un voleur - to leave like a thief.
So, who started it? The question of who started this passive-aggressive spat is yet to be answered. Some reports date the origin of the English French leave back to the 1850s and closely tie it to the Napoleonic campaigns and the supposed cowardice of French soldiers.
On the other hand, the French idiom filer à l'anglaise has two stories: 1- Some French language experts explain this expression was only aimed at creditors, who were called les Anglais in the 1500s. People then used to leave quickly when les Anglais were around, resulting in filer à l'anglaise. In the same vein, the 19th century verb anglaiser - which has totally disappeared today - used to mean voler, to steal. 2- There is also a theory claiming the expression is a small French revenge towards the the English for coining the French leave idiom in the first place.
While to this day no one knows for sure who started the squabble, both cultures managed to spread their respective versions throughout Europe, as one can see here:
German: französischen Abschied nehmen ("to take a French leave")
Italian: andarsene all'inglese ("to leave English style")
Polish: wyjść po angielsku ("to leave English style")
Portuguese: saída à francesa ("to leave French style")
Russian: уйти по-английски (ujti po-anglijski) ("to leave English style")
Spanish: despedida a la francesa ("goodbye in the French way", "French farewell")
Wallon: spiter a l'inglesse ("to leave English style")
Hungarian: angolosan távozik ("to leave English style")
Czech: zmizet po anglicku ("to leave English style")
Il file à l'anglaise, personne ne le voit jamais partir.
He takes French leave, no one ever sees him going.
Marcel Proust’s In Search of Lost Time:
Je vous suis, me dit-il, mais nous ne pouvons pas partir à l'anglaise. Allons dire au revoir à Mme Verdurin.
I'll follow you, he told me, but we can't leave in the English way. Let's say goodbye to Mrs Verdurin.