Some well-intentioned commentators say the G20 has spread itself too widely and should concentrate on just a few central issues, such as the need to get global growth going again and reduce unemployment or to cut high debt levels.

But on such key economic issues there is widespread disagreement even within countries not only about what are the right policies but also over the order to introduce the steps.

To take just the single most-burning issue - austerity measures to trim government spending and get on top of debt - most developing countries - quite rightly - complain that the financial crisis in the US and Europe brought about the mess that the world is in, and the rich countries should get their houses in order. But how, how deeply and how quickly should they cut spending?

If the rich West tries the painful short, sharp shock of austerity, more jobs will be lost and growth will fall, along with demand for imports, sending shock waves around the world. Repercussions of austerity in Britain, with the fear of a dreaded triple-dip recession, have caused the International Monetary Fund, traditionally regarded as the dispenser of painful medicine, to suggest that London should consider a plan B, with less austerity.

The old developed countries have yet to understand the need for far-reaching economic and societal changes. How can they continue to live like princes, protected by health and welfare systems that their countries' battered budgets cannot afford, if their people are less flexible, less productive and less educated than the populations of up-and-coming countries?

That is the question that the developing members of the G20 are asking, and you can expect an increasingly bitter edge.

If one is being kind, one might say the G20 is still a work in progress, not least because its emergence as the putative global economic body represents a struggle between the old order of a world ruled by Washington and its supporters and the new, yet-to-be-established order where several conflicting powers are fighting for dominance.

The star of Dominique Strauss-Kahn, former French finance minister and former managing director of the IMF, has faded because of his wayward personal life. But DSK was a good head of the IMF and a perceptive observer of the world he had to deal with. Just before he left the IMF, he admitted that the 2008 financial crisis also "devastated the intellectual foundations of the global economic order of the last quarter century".

He acidly described the Washington consensus as a "number of basic mantras. Deregulation and privatisation would unleash growth and prosperity. Financial markets would channel resources to the most productive areas and police themselves effectively. And the rising tide of globalisation would lift all boats. This all came down with the crashing crisis."

So there are fierce arguments about what to do and about who should take the lead and who should bear the biggest burden of change and adjustment.

The group accounts for 85 to 90 per cent of global gross domestic product, more than 80 per cent of global trade, and 65 per cent of the world's population. Even so, almost 90 per cent of the world's countries are not G20 members, including 25 of the 34 IMF advanced economies.

Agendas have ballooned and communiqués become laundry lists as G20 discussions are driven by domestic considerations.

There's a lot to think about.

Without a better attitude of give and take and some far-seeing leader who appreciates that a global view is necessary, not merely national strength, the G20 will continue to be a glittering expensive circus, tickets available only to the rich and famous.