Excerpt taken from the book The Story of French (Ch. 1)

At the beginning of our research, Jean-Benoît travelled to the island of Jersey, a mere sixteen kilometres off the coast of Normandy in the English Channel. The island is a kind of pastoral dreamscape, with small trails criss-crossing a beautifully unassuming countryside of green vales, medieval castles and Celtic stone monuments. At low tide its surface area extends to a grand total of fourteen by ten kilometres. A dependency of the British Crown, Jersey is a tax haven that harbours five times more foreign capital than Monaco. Like Monaco, it won this role thanks to a combination of handy location, beautiful scenery and unusual historical circumstances. Amazingly, over the centuries this tiny island has managed to retain its autonomy: it’s not even considered a part of the European Union. It has managed to hold on to an ancient Anglo-Norman law system that dates back a thousand years, and that financiers and the wealthy find particularly well adapted for sheltering their money. 

But Jean-Benoît was there to see—actually, to hear —another remarkable historical relic: the Jèrriais language. The island’s English-speaking majority today calls it “Norman French.” To an untrained ear, the language sounds like mispronounced French, but it is effectively a tongue of its own, one of the last surviving examples of the old Norman dialect—one of the source languages of French—that was exported to English in the eleventh century. Jèrriais has its own phonetics, syntax and lexicon. One of its most striking features is its use of the th sound, which is common in English but nonexistent in standard French. For words such as father, mother and brother, Jèrriais speakers say paithe, maithe and fraithe, rather than the French père, mère and frère.

In fact, roughly three-quarters of the vocabulary and grammar of French and Jèrriais overlap, which gives the two languages more in common than French and Haitian Creole, for example. For a francophone with a good ear and tolerance for variation, most of the conversation is intelligible.