The consequence, as revealed by the latest census, is that white Brits are now in a minority in London, making up just 45% of its residents.
So where have they gone to - and why did they leave?
The movement of the white British is often characterised as white flight - the indigenous population forced out of their neighbourhoods by foreign migrants. That may be part of the story, but I think the evidence suggests it is also about working class aspiration and economic success.
Trying to track internal migrants is never easy. Just because the population of one place has fallen and another has risen does not mean residents moved between them. But there are some clues as to where London's white British migrated to between the censuses of 2001 and 2011.
While the capital's white British population fell by 620,000, the white British population in the rest of England and Wales increased by 220,000. The overall fall of 400,000 is explained by a low birth rate and emigration.
These maps show the change to the white British population in local authorities in England and Wales between 2001 and 2011.
Voice of Russia, BBC