White British people will be a minority in their own country by 2066 if current immigration levels continue, a population expert has claimed.
Professor David Coleman, of Oxford University, said the demographic group would make up less than half the population in "little more" than 50 years.
He said the decline will be caused by record-breaking levels of immigration and the migration of thousands of British nationals abroad over the coming decades.
Prof Coleman made the comments as the Migration Advisory Board prepares to announce recommendations on the Government's proposed cap on migrant workers from outside the EU.
Writing in an article for Prospect magazine, Mr Coleman said: "Inflows (of migrants) of the last decade have been more sudden and on a bigger scale than ever before.
"The consequent increases in population and changes in its composition have caused concern about economic opportunities, housing, local character and national identity. Moreover, if inflows continue on a similar scale, they will transform the demography of this country."
The demographic analyst said projections by the Office for National Statistics show that rising numbers of immigrants, combined with trends in fertility and survival, will see Britain's population rise to 77 million by 2051 - the equivalent to adding the population of the Netherlands. He said the population would then rise to 85 million by 2083.
Referring to white British people becoming a minority, the population expert added: "The 50% benchmark has no special demographic significance, but it would have a considerable psychological and political impact.
"The transition to a 'majority minority' population, whenever it happens, would represent an enormous change to national identity - cultural, political, economic and religious.
"In Britain, judging by the opposition to high immigration reported in opinion polls over recent years, it seems likely that such developments would be unwelcome."