 DNA provides a direct record of the effects of immigration on the population.Studies of DNA suggest that the biological influence on Britain of immigration from the Norman conquests up till the 20th century was small; The native population's genetics was marked more by stability than change.For the settlement/invasion of Great Britain before the arrival of the Romans see the article Prehistoric settlement of Great Britain and Ireland

The first Roman invasion of Great Britain was led by Julius Caesar in 55 BC; the second, a year later in 54 BC.