Nobody. All it needs is a politician with balls. Someone has to get us out cleanly without our leaving being at the EU's whim. They are never going to let us go when May has negotiated a free lunch for them in perpetuity. If it comes to another referendum (which would be an EU-esque travesty in itself), then a clean break, no-deal it has to be as the only viable option to get this country out of the mess it finds itself in.
Staying in the EU is no panacea because the common currency is not renogtiable, so the undervalued German component can pump out its wares to the detriment of the rest of the EU ad infinitum. Like it or not, the only mechanism to give this country any hope of having a balanced and viable economy is to be free of any interference from Brussels. It won't be easy, but does at least have a chance of success, as opposed to remaining in or being subservient to the EU, which would not.