http://en.wikipedia.org/wiki/List_of_countries_ranked_by_ethnic_and_cultural_diversity_level
I wondered about that statement. Turns out the UK is more ethnically diverse than France - though that includes Wales and Scotland, naturally.
Off the top of my head, Sterling, Johnson, Sturridge could have played for Jamaica, Welbeck for Ghana, Jagielka for Poland, Barkley for Nigeria. They just seem less likely to do so. I still doubt there is a much diversity as France, though.
Apparently so