It is not often that you get a chance to test a political theory in practice, particularly when it is one of global reach. A few years ago I read an essay in The New York Review of Books by Professor John Gray of the London School of Economics, making the point that however porous globalization may have made national frontiers, it had done nothing to homogenize polities around the world.

To the contrary, there was rich variety across the whole spectrum of political organisation, from North Korean dictatorship at one extreme to -- take your pick -- the most egalitarian of democracies at the other. This sparked the thought in me that globalization might even be a spur to national feeling, as people fought to preserve their identities against the rising sludge of homogenization. So, when I was asked to make a television documentary series examining power in six great cities of the world, it looked like a perfect opportunity to test the limits of globalization. And so it proved.

Alien hinterlands

When I got to examine the six cities -- Mumbai, Moscow, New York, Rome, Los Angeles and London -- another thought struck. Did these places have more in common with each other than with their own national hinterlands? I remembered from my time in the US how alien NYC and LA were to the great mass of the population living in America's middle and south. It wasn't until I retired from the Diplomatic Service in 2003, and started travelling around Britain, that I came to realise how utterly different London was from the rest of the country.

In Italy, a relatively young nation, Rome's long history as a great city-state is its defining characteristic. Moscow has been a city-state for centuries. But so is Mumbai today, marked out by its wealth, industry, culture and population. It contributes 40 per cent of India's tax take. It is an attribute that all six share: they are city-states.

Of course, at a rather superficial level, you will find the same things everywhere. Designer fashion, Italian restaurants, Irish-themed pubs and American fast food are rampant in all the cities. It's a shock to eat a sandwich in a Subway store in Moscow or a hamburger at TGI Friday's in Mumbai (though eating a Bangladeshi meal in a Somali cafe on the Whitechapel Road seemed to me perfectly normal).

Marching to their own beat

Some of the very rich appear to be in perpetual motion as they flit from home to home around the world, occasionally returning to the nest like migratory birds. Nita Ambani, wife of one of the richest men in the world, protested to me rather unconvincingly that her grandiose, fitfully inhabited, 27-storey house in Mumbai was the only place she and her family could call home. In Moscow, I interviewed a well-connected Russian lawyer who has a home on Wimbledon Common. Bollywood's Shah Rukh Khan, the biggest film star in the world, apparently has a flat off Grosvenor Square.

Despite all this, don't think that these cities are starting to look, and behave, like each other. Each marches to its own beat. That is the main conclusion I have drawn from our film series. What to make, for instance, of the inchoate city of Los Angeles? Most of its inhabitants are now Latino, a force increasingly to be reckoned with. Just where is this leading?

Vibrant, cosmopolitan

Or Rome?

Here to my astonishment -- compare and contrast with NYPD headquarters -- the man in charge of hunting down the Mafia works from an agreeable urban palazzo, with no evident security apart from a rackety old X-ray machine and a steel-plated o¸ ce door. And he survived an assassination attempt.

Or Moscow?

Replete with consumer goods, and a spanking new urban middle class, it is a hotbed of opposition to Putin. It reminded me of embourgeoise Madrid in the 1970s, impatient with the censorship and corruption of Franco's declining regime.

Or London?

Vibrant, cosmopolitan and open to all the talents it may be. But, an Englishman's word was once his bond. No more, I fear, after so many recent scandals. To find the old-fashioned values that used to characterise London, I had to go to India, to visit the Gujarati diamond traders of Mumbai, where enormous deals are still sealed by a simple handshake.

Christopher Meyer is presenter of Networks of Power on Sky Atlantic

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