London’s mayoral contest is slowly limbering to life. ... The leadership of a great city should be fought over as if it mattered. So what’s missing? At the moment what’s missing is what makes London great – ideas. Just as the general election was bereft of exciting ideas, so is London’s contest.

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For prospective mayors, the central challenge of leadership flows from this dual character. On the one hand, they need to generate wealth and jobs, and keep on attracting the energetic and ambitious. On the other, they need smart ways to share the opportunities and benefits beyond a small elite.

Achieving that double success is far from easy. Los Angeles combines vast wealth with entrenched poverty and crime. Paris is divided between its glossy centre and its crumbling and troubled banlieues. New York swung left in 2013 because too little was being done to bridge the gap between the haves and have-nots. But everywhere cities are once again where ambitious politicians want to make their names, where companies want to launch and where universities seem to thrive best.

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This is the heart of the challenge for any great city: how to link the top and bottom, the rich and the poor, the fast and the slow. Not long ago, everywhere wanted to copy Silicon Valley, and it remains true that every city would love to give birth to the next Facebook or Twitter. But they also now recognise that the Silicon Valley model achieved very little “trickle-down” of wealth. Most Americans now earn less than they did a few decades ago, even as a tiny proportion have become immensely rich. And so the search is on for better models of economic growth that overhaul schooling to better fit where the jobs are coming from, and get big firms to open their doors to the poor and marginalised.

London’s mayor will have to be plausible both for the people in the City, and in “tech city”, who have never had it so good, and for others who watch on from the sidelines, either out of work altogether or trapped in insecure low paid work that’s going nowhere. A few ideas are floating around about affordable housing. But we risk ending up with a campaign that confirms the fear that politics has fallen behind society, stuck in a rut of predictable positions and low expectations.

Devolution was meant to be about unleashing ambitions and energies – and in Scotland that is exactly what it’s done. But for London and for England’s other cities, we’re still waiting.