Will Mega Cities Usher In A New Era Of City-States?

"Greater Shanghai has a population that has passed 20 million. The sprawl of Mexico City is estimated to house another 20 million. And Mumbai too."

Could these and other cities outgrow their national governments and shift towards more local power?

"Economically, many of the world's great cities are already divorced from their nation-states, with their main streams of investment come from other great cities.

'The most important place to London is New York and to New York is London and Tokyo,' says Sociologist Professor Richard Sennett, one of a number of academics carrying out research into the evolution of cities."

Even London Mayor Ken Livingstone recently bemused that the success of Singapore, the most well-known city-state in the world, demonstrates the opportunity that cities gain when they have more control over government policies.