>And conversely, when Brits go abroad, they should learn the language of the land, rather than assume the world speaks English. Living in a British/English enclave is not the way to integrate.
I agree with you that people should make an effort to at least learn some of the language however it just so happens that English is the de facto international business language and the world's most widely spoken language. If you are an international business traveller it's not going to be practical to learn every single language on Earth, Esperanto was a valiant effort to please every country politically but never took off. Good luck trying to simultaneously learn Arabic, Mandarin, Russian, German, French, Spanish and Japanese; only a few thousand more to learn after those.