There was a separation between the noble french and the vulgar Old English.
Or as I wrote in my comment: Who cares about the language of peasants
I found a nice source for this assumption
Middle English (1100-circa 1500 AD): After William the Conqueror, the Duke of Normandy, invaded and conquered England in 1066 AD with his armies and became king, he brought his nobles, who spoke French, to be the new government. The Old French took over as the language of the court, administration, and culture. Latin was mostly used for written language, especially that of the Church. Meanwhile, The English language, as the of the now lower class, was considered a vulgar tongue.
By about 1200, England and France had split. English changed a lot, because it was mostly being spoken instead of written for about 300 years. The use of Old English came back, but with many French words added. This language is called Middle English. Most of the words embedded in the English vocabulary are words of power, such as crown, castle, court, parliament, army, mansion, gown, beauty, banquet, art, poet, romance, duke, servant, peasant, traitor and governor. ("Language Timeline", The British Library Board)
Very intersting :
Because the English underclass cooked for the Norman upper class, the words for most domestic animals are English (ox, cow, calf, sheep, swine, deer) while the words for the meats derived from them are French (beef, veal, mutton, pork, bacon, venison). ("The Origin and History of the English Language", Kryss Katsiavriades)
Another source notes, that exaclty the period you asked, is the period, where Old English changed to Middle English:
with the Norman Conquest, the English language underwent some dramatic changes. Anglo-Norman, or early Middle English, had direct effects that can still be seen today. Some of our words with an Anglo-Norman origin include chamber, judge, archer, flour, guarantee, parliament, jury, college, and adventure. In addition to new vocabulary words, English grammar underwent changes, too. After the end of the fourteenth century, early Middle English transformed into late Middle English.