The scene at Valentines High School in Ilford, Essex, at 10.50 on a Wednesday morning is a familiar one: it is break time and groups of teenagers congregate to chat, gossip and flirt. Snippets of conversations that drift across the playground reveal universal concerns - girlfriends, boyfriends, Big Brother, Arsenal Football Club - and also a myriad accents: from Urdu to Arabic, Polish to Turkish, Albanian to Essex. The 1,300 students at Valentines speak more than 50 languages, and...