It may take months to discover whether the actions taken by last week's Group of 20 summit in London are enough to rescue the world economy from a prolonged recession, if not depression. The substance of its conclusions will have to convince capital markets, global financial institutions, investors and humble consumers that they can start to spend, borrow or lend again.

But the symbolism of the event may be more important than the substance. For even if the G20 countries are a strange ad hoc selection, initially brought together by the Asian financial crisis in 1997, they represent a whole new element in the world order. They are not the Group of Seven - the club of western powers and Japan - or the G8 (the G7 plus Russia). The use of the G20 at this moment of global crisis is a clear indication that the old order has outlived its time.

Another pointer came four months ago when the US National Intelligence Council, part of Washington's security apparatus, published a startling forecast. The international system as constructed after the second world war would, it predicted, be "unrecognisable" by 2025, thanks to globalisation, the rise of emerging powers and "an historic transfer of relative wealth and economic power from west to east".