What year did the Romans leave Britain after invading?

After the Romans departed, being recalled to face the invasions into Western Europe, they left rule to Romanised British kings, who fought amongst themselves and imported soldiers from the Germanic Angles, Saxons and Jutes. These soldiers realised the opportunity and imported more from their own tribes, and took over from the Britons.

Then came waves of Vikings to the east coast who, having looted it bare, settled there to make a living.

Then came the Normans (Norse Men), who were Vikings who, having looted northern France bare, had settled there (Normandy) to make a living. They took the oppportunity of seizing the south of Britain while more Vikings from Norway provided a distraction by invading the north of England (Angle Land).