In a small town in the Black Country last night, a political rally took place which should have the two main parties feeling extremely nervous. Willenhall, on the outskirts of Wolverhampton, doesn’t even have a train station. Yet well over a thousand supporters packed out a wedding venue to see the Brexit Party’s latest rally, filling every seat, standing in the aisles and exhibiting a greater enthusiasm than has been seen in British politics since the rise of Jeremy Corbyn.