This is a UN report from 2001, and is worth a read.
http://www.un.org/esa/population/publications/migration/migration.htmThis is the bit about the UK:
http://www.un.org/esa/population/publications/ReplMigED/UK.pdfBasically it says that for the UK to remain with the economic power it had in 1995, it must take 59.8m immigrants by 2050 (near enough a 1m a year), and raise retirement to 72. By 2050, 60% of the population would be would be post-1995 immigrants or their descendants.
Europe as a whole must take in almost 1.4 billion immigrants in the same period, at an average of 25.2 million a year. By 2050, the population of Europe would have grown to 2.3 billion out of which 1.7 billion, or almost three quarters, would be post-1995 immigrants or their descendants.
