"I see claims that over 9 million people living in the United Kingdom are foreign-born if you include the children they produced. That is 15%, not 5% as mentioned above. When they concentrate in their own neighborhoods and continue to speak their native languages, they are not really very "British"."

First - Where do you see these claims? can you provide a link or is this a figment of your imagination?

Second - "When they concentrate in their own neighborhoods and continue to speak their native languages, they are not really very "British""

As I have posted here before, I lived in the Indian/south Asian ghetto of highfields in Leicester for a year and a half.

The myths propagated about areas like this by people who never go into those areas except to pass through them have very little in common with the facts.

British youth of Asian origin in Leicester talk English with strong Leicester accents and participate fully with society as a whole.

There are many other assumptions in PDQ's generalization above that I would love to challenge but I am utterly exhausted at the thought.