When he gave the green light to a further tranche of regional mayors, George Osborne could not have predicted he was setting up a fascinating power play over the next half decade around how the country is run and the future of its public services. But that is what he has created, between a block of energised and powerful regional Labour mayors and a likely future Labour government.

Labour now runs 11 of the 12 combined mayoralties representing the country's largest conurbations and major cities. Only Ben Houchen, in the Tees Valley, is left flying the Conservative flag following last month's mayoral elections.