Chancellor George Osborne has set the pace on the city devolution agenda, providing not only clarity but also urgency. Greater Manchester already has an interim mayor; the Devolution Bill was launched in late May, and (hopefully) will be on the statute books by early 2016.

In response, places and local politicians are now quickly reviewing, and in many instances revising, their positions in relation to combined authorities and mayors. But it would be naive to assume that all the opposition to metro-mayors has disappeared overnight. The politics that underpin the opposition still exist.

That’s why we expect the mayors debate to shift from one about whether to have a mayor, to one about how powerful the mayor should be.

This shift will be helped by the deliberately generic nature of most of the bill: that, in principle, offers scope for different mayoral models to emerge in different places, ranging from executive-style mayors, akin to London*, to “ceremonial” style-mayors with very limited executive powers.

As places consider their options, the temptation for some will be to meet the chancellor’s “Metro Mayor” test by introducing the latter type of mayor. This would be a mistake for several reasons.

Firstly, there is no automatic right to devolution: even if a place puts together a devolution proposal that includes a combined authority and a mayor, there is no obligation on the government to accept it. The Bill is clear that the power to agree devolution settlements will lie with the communities secretary. Given the stated policy positions of the chancellor and others in government, any attempt to create a purely ceremonial mayor in order to secure additional powers would very likely fail.

Secondly, the value of an executive mayor comes from the ability to combine hard and soft powers to actually get things done. That’s particularly true when it comes to more contentious things: prioritising investment in one place of the city region over another, or introducing a council tax precept, or closing the A&E of a hospital. Relying on consensus, diplomacy and exhortation – as a ceremonial mayor will be forced to do – only gets you so far. Being able to take action is important.

Third, wielding significant powers over public services – planning, crime, health, fire, transport – at the city-region level requires a degree of direct public accountability that doesn’t currently exist within the local government system. While there are other options for improving governance, accountability and scrutiny, none of them match the mayoral model for providing that direct connection between decision-maker and the electorate.

Finally, the public currently have little faith that politicians can change things for the better. Introducing a mayor with limited power to get things done – and, just as importantly, to be seen to get things done – is likely to further erode the belief among the public that politicians can be a force for good.

Having powerful executive mayors will be good for those cities that have them and for the country as a whole. Cities need to be bold and seize the initiative, take the chancellor at his word and set out how they will introduce powerful metro mayors. In return, they will get substantial control of their services – planning, housing, skills, police, transport and health – and some fiscal discretion that will enable their economies to grow, and create the good jobs and provide the quality public services that their residents want.

Andrew Carter is acting chief executive of the Centre for Cities.

This is an edited version of an article first posted on the think tank’s blog

* It’s worth noting that by international standards the London mayor is not very powerful – but that’s another story.