Elizabeth Janet Gray's young reader's novel Adam of the Road does an excellent job of portraying England during the Middle Ages. One aspect Gray portrays well is the various languages and dialects spoken in England during this time period.
By this period, most of those in England spoke what scholars have dubbed Middle English, which stemmed from Old English. Middle English also had multiple dialects, which Gray hints at in her book. For example, in the early pages of the book, the narrator and protagonist Adam reflects on how when he was at the abbey school, during free times, the other boys would ask him to play his harp. As he played, he would sing for them the stories his father, whom he calls Roger the minstrel, told him. He further notes that, since he was from the north, having a heavier dialect than those from the midlands, the boys would make fun of him. In using the term midlands, the author is referring to the areas officially known as East-Midland and West-Midland. London became an area that spoke the East-Midland dialect. Other areas included in Lancashire, Cheshire, Suffolk, and Norfolk. Since London became an area that spoke the midlands' dialect, this dialect became seen as the more "proper" way to speak. In contrast to the midlands' dialects, the Northern Middle English dialect was heavier, placing different inflections on nouns and verbs and using inventive syntax. Northern areas of England include such counties as Northumberland, Durham, Yorkshire, and Humber. Hence, when we speak of different languages being spoken in England during the Middle Ages, we can speak of different dialects, which is a variety of a language that can be so different that even grammar is different. Oftentimes, those who speak different dialects of one language actually cannot understand each other though that's not always the case.
Gray also makes a reference to language when the narrator Adam talks about the "language of the court folk" (p. 16). In the same scene above, Adam further notes that when the midlanders made fun of him for his northern dialect, he turned the tables on them by speaking in French, saying, "Not many of these sons of franklins and burgesses knew the language of the court folk" (p. 16). Adam knows French because his father is studying in France in order to be a minstrel at England's court. Though French was naturally spoken in the royal court of France, it was also the language of the educated upper class in general; therefore, French would have been spoken in the English court as well.
Yet another language spoken in England during this time period would be Latin. Adam explains that the masters at his abbey school spoke in and had the boys learn Latin, "for all their talk in school was in Latin" (p. 17). Hence, in the same way that the language of the court was French, the language of the scholars was Latin.