Several years ago, speaking at a political party fringe meeting on devolution, the then shadow communities' secretary Hilary Benn posed his very own version of the West Lothian question for local government.

Why, he asked, could an MP for Ealing, where he had been a councillor, vote on decisions about buses in Leeds, where he was an MP, but devolution in London meant the same Ealing MP had no say on buses in his own area.