The Bill of Rights doesn't mention that freedom of speech is restricted to a special class of establishment journalists. Freedom of speech is a universal property right, regardless of what the establishment-media gatekeepers say.
The fruit of the Enlightenment has been the growth and centralization of the state, at the expense of all other institutions. The material plenty we enjoy today are in spite of this change, not because of it.
London is a major global hub, and a hard Brexit wouldn't change that. But one of the best possible outcomes of Brexit could be a move toward real free trade beyond the faux "free trade" of the EU bloc.