I thought it was pretty high. I found this:
UK immigration: 9 out of 10 jobs created last year went to foreign nationals | Mail Online
I think you'll find that the "foreign nationals" concerned were EU citizens. There is no restriction on EU nationals coming here for work (and due to the troubles in the eurozone, they are flooding in). There is a points system for people outside the EU.
The other point to make is that Britain has a population of 63 million, and London's population is 7 million. Pretending that London is the majority of Britain is mathematically incorrect!
Lets put it this way - thanks to the low amount of ethnic minorities and very high rates of assimilation, I'm willing to bet that Britain in 100 years time is very similar to now, but the USA will have changed out of all recognition...