Braveheart–What historical goof is in the movie?

The Historical Blunder in Braveheart

In the movie the princess makes a snide comment in French about her husband, the English prince, and no one but her French maids understand a word she says. But at this period of time in England in the late 1290’s, everyone would have understood French — that’s the language they were speaking, too!

French was the language spoken by all the royalty and government officials in England from the time of William the Conqueror (in 1066) to the time of Chaucer in the late 1300’s. French was the only language used other than Latin in all the English law courts, churches, and homes of the nobility. English was learned on the side, if at all, though it endured as the dominant language of the lowly common folk. It was almost 100 years after the time of William Wallace, the main character in the movie, that English once again became the dominant language of English royalty and government officials.