North Germanic unit, from which the emperor's bodyguard was drawn and continued to serve the empire until the early 15th century. However, the population of England at home remained largely Anglo-Saxon; for them, little changed immediately except that their Anglo-Saxon lord was replaced by a Norman lord. The chronicler Orderic Vitalis, who was the product of an Anglo-Norman marriage, writes: "And so the English groaned aloud for their lost liberty and plotted ceaselessly to find some way of shaking off a yoke that was so intolerable and unaccustomed". The inhabitants of the North and Scotland never warmed to the Normans following the Harrying of the North (1069–1070), where William, according to the Anglo Saxon Chronicle utterly "ravaged and laid waste that shire". Many Anglo-Saxon people needed to learn Norman French to communicate with their rulers, but it is clear that among themselves they kept speaking Old English, which meant that England was in an interesting tri-lingual situation: Anglo-Saxon for the common people, Latin for the Church, and Norman French for the administrators, the nobility, and the law courts. In this time, and because of the cultural shock of the Conquest, Anglo-Saxon began to change very rapidly, and by 1200 or so, it was no longer Anglo-Saxon English, but early Middle English. But this language had deep roots in Anglo-Saxon, which was being spoken much later than 1066. Research has shown that a form of Anglo-Saxon was still being spoken, and not merely among uneducated peasants, into the thirteenth century in the West Midlands. This was J.R.R. Tolkien's major scholarly discovery when he studied a group of texts written in early Middle English called the Katherine Group. Tolkien noticed that a subtle distinction preserved in these texts indicated that Old English had continued to be spoken far longer than anyone had supposed. Old English had been a central mark of the Anglo-Saxon cultural identity. With the passing of time, however, and particularly following the Norman conquest of England, this language changed significantly, and although some people (for example the scribe known as the Tremulous Hand of Worcester) could still read Old English into the thirteenth century, it fell out of use and the texts became useless. The Exeter Book, for example, seems to have been used to press gold leaf and at one point had a pot of fish-based glue sitting on top of it. For Michael Drout this symbolises the