A non-English speaking pax travelling on a British airline, seated at the 737 over-wing exit (a 'self-help' exit as it is known) would have to be moved, as it would not be possible for a CC to adequately brief them before departure, or for them to understand CC instructions in an emergency.
Not quite... In my British airline on some flights it would be impossible to find enough English speaking passengers. Therefore, we brief in other languages (all of my colleagues are at the very least bi-lingual) or make ourselves understood in some way. (Illustrations on the safety card / self help exit panels are useful).