Sadiq Khan, the Mayor of London, spoke exclusively to CNBC Thursday about the U.K.'s departure from the European Single market. #Brexit will make London poorer, the mayor said, and it "would be bad for... Europe too." Khan elaborates: "The concern is some of these businesses may decide to leave London and go not just maybe Paris, Madrid or Berlin, but leave Europe altogether, and go to Hong Kong, Singapore." Do you think Brexit will cause businesses to leave the EU? Khan told CNBC that he has met with business leaders, executives and entrepreneurs across London and the feedback is that "the access to a single market (and) the continued ability to attract talent is important for jobs, growth and prosperity."