Devolution is hard. it is not for lack of trying that, a decade after David Cameron promised 'a radical decentralisation of power from Whitehall', Britain remains one of the most centralised countries in the developed world.

But the gains achieved so far prove the value of the eventual prize. Metro mayors, with influence over infrastructure and public services, have brought focus, energy and local knowledge to Britain's municipal government. Their voices echo on the national stage such that Whitehall can no longer ignore the needs of Britain's regional cities