Historical immigration to Great Britain
Modern humans inhabited Great Britain long before the arrival of the Romans in the first century BC, an era for which no written historical records exist. Following the Roman withdrawal, there was a substantial migration of Germanics, specifically, the Angles, the Saxons, and the Jutes, spanning from the 5th to the 7th centuries AD, leading to the formation of England by 12 July 927.
Source: Wikipedia — Historical immigration to Great Britain (CC BY-SA 4.0)