The language of course is English. It's universal. It is somewhat a big factor why many people from all over the world have crossed to England or particularly in London. There's no language barrier for professionals not hindering them to establish their careers or start their desirable career path. Another thing is, the number of job vacancies has increased. Growth in average earnings, both excluding and including bonuses, has increased. Sounds good eh!
London jobs are not also difficult to find. Search 1000s of London jobs online. There are lots of online job tools totally free service to all jobseekers. Try this online job seeker for jobs in London.