'A summary history of immigration to Britain.'
"There have always been episodes of migration to Britain but, as this paper demonstrates, those episodes were small and demographically insignificant until the Second World War.
A study of official census records from 1851 until the present shows that the number of people born abroad living in Britain was very small until the middle of the twentieth century and that the growth of this population between censuses was quite slow. Indeed, in the eighty years between 1851 and 1931, the population born abroad increased by only about one million.
It increased slowly after the Second World War, growing by less than two million in the forty years between 1951 and 1991. In the late 1990s the pace and scale of migration increased to a level without historical precedent. Indeed the foreign born population of England and Wales more than doubled, increasing by nearly four million in the twenty years between the 1991 and 2011 censuses.
It has now reached 13.4% of our population. This massive increase dwarfs the scale of any previous inflow in our history."2. Measuring historic immigration
"The Census began to record people’s country of birth from 1851. Estimating the size of the foreign born population before that is much more difficult, but historical records give us some idea as to the scale of immigration before the mid-19th century.3. Immigration before the first census
It was not until 1964 that the international passenger survey was established; it provides a broad picture of those entering and leaving the country on an annual basis. In 1991 a more sophisticated measurement of immigration called the Long Term International Migration estimates was put in place."
"It has been asserted that 'the basic human stock of England has been settled and relatively homogeneous since time immemorial’ but there have always been some movements of people to (and from) Britain. Defining the first occurrence of immigration to the British Isles is difficult and a point of controversy.The rest of this article and the embedded notes may be found here.
It is important to note that, although we can estimate the size of the population and of migrations to Britain before records began, we cannot be precise about a period before documentary records survive. Though it was almost certainly inhabited in a previous period, the area that is today Britain was uninhabitable during the ice age, with the oldest settled populations only migrating here after the end of the glacial period some 25,000 years ago.
The period that followed until the Roman invasion is known as pre-history due to the lack of written records and as such little is known of the people that settled during that period. There is some controversy however as to whether the advent of agriculture in Britain 10,000 years ago was the result of cultural diffusion or the migration of peoples. In the first millennium AD, Britain experienced considerable inward flows of people although estimates of invaders and settlers are still uncertain."