Really? I doubt that! I teach inner city Bradford and I only ever have around 5 children in my class who don't have English as a first language (and they all speak English fluently). In fact, the kids don't ever speak their first language in school as they are far too shy about it, even when we have a new child who doesn't speak English initially, the kids refuse to translate, or go into the cloakroom to whisper it, as they are so embarrassed (no idea why).
actually there is one thing that i do agree with in that article and that is london is becoming an oasis in a desert and needs addressing.