In our April YouGov poll, one quarter of our respondents said there should be no arbitrary limit on the proportion of the UK’s population which is immigrant; while two-thirds think a proportion of over 15% is okay.
Since the migrant and ethnic minority populations are still below 10%, we have a way to go before Britons feel threatened by pure numbers.
Trevor Phillips, 'Sleepwalking To Segregation'.
The 'way to go' being the time lag neccesary for the 19.2% of children born in England (to a mother who was herself born abroad) to grow up. Not that long.