England was never a vassal of Normandy. Ever since the conquest of 1066, it was ruled in a personal union (two states ruled by the same people but without necessarily having the same government or laws; other examples include the Holy Roman-Spanish union under Charles V or England under the Hanoverian dynasty) by the Dukes of Normandy or by members of their family. As an example, William I had split his lands between his sons, giving Normandy to the eldest, Robert (1051-1134), England to the secondborn, William Rufus (1056-1100) and funds to the youngest, Henry (1068-1135).

The original Norman dynasty died out in 1135 with the death of William's son, the aforementioned Henry, who had ended up king after William Rufus' death and a war with his eldest brother Robert. Though he had originally named his daughter Matilda as his heir, the throne was taken by his nephew, Stephen of Blois (1092-1154), the son of William's daughter Adela. The ensuing civil war is, today, known as the Anarchy (1135-1153), pitting the supporters of Stephen against those of Matilda (she was married to Geoffrey, Count of Anjou (1113-1151); the Angevins were traditional enemies of the Normans). During that period, Geoffrey of Anjou conquered Normandy.

After the Anarchy ended when Stephen agreed to recognize Matilda's son Henry (the future Henry II, 1133-1189) as his heir, Normandy remained in a personal union with England, while still being a legal vassal of France (Henry II was prevented from attacking Toulouse because the King of France, Louis VII (1120-1180), was currently staying there). Through his Norman and Angevin heritage and his marriage to powerful heiress Eleanor, Duchess of Aquitaine (1122-1204), Henry controlled approximately half of France, from Normandy to the Pyrenees; his dominions are known (anachronistically) as the Angevin Empire today.

Louis VII's son, Philip II Augustus (1165-1223), was an altogether different sort from his father, and warred against first Henry then his sons Richard (Richard the Lionheart, 1157-1199) and John (John Lackland, 1166-1216) to regain England's continental territories. Normandy was lost to England in 1204, which was further cemented when an Anglo-Flemish-Holy Roman coalition was crushed by France at the Battle of Bouvines in 1214.

However, England's monarchy continued to be very French; the English crown had broad lands on the continents, with the entire Duchy of Aquitaine still in a personal union. John's grandson Edward I (Edward Longshanks, 1239-1307) was required to provide military service in Philip III of France (1245-1285) and swore homage to Philip III's son Philip IV (1268-1314).

It was not under Edward III (1312-1377)'s reign that Parliament was opened with an English speech, in 1362, thus nearly three centuries after the Conquest, and Edward's grandson Henry IV (1367-1413) was the first king of England to speak English as his mother tongue. Henry IV's son Henry V (1386-1422) of Shakespearean fame was the first to promote the use of English language in government rather than French, and was the first king to use English in his personal correspondence.