The question becomes what if Ecuador grants him diplomatic immunity? Or if they sneak him out? Surely the UK is not searching diplomatic vehicles. They could smuggle him out to an undisclosed airport and send him to Ecuador.
It's long been debated here on El Reg if that solution was viable, the general consensus being that it wasn't, given that host nation hosting said diplomat (the UK in this case) have to approve all diplomats. Ecuador went ahead and tried anyway, granting Asshinge citizenship of Ecuador and applying for him to be made a diplomat. Now, Asshinge is an Ecuadorian citizen and still not a diplomat as the UK refused the application. So not viable a viable way out.