George W. Bush entered office arguing for “regime change” in Iraq. He leaves it with global calls for regime change in finance. That heads of state from the biggest emerging economies are attending the crisis summit in Washington alongside their “emerged” peers shows that business is no longer as usual, even if, as Brazil’s foreign minister put it, they have been invited only for the coffee breaks.

The G20 faces two main challenges: stopping the world sliding into a depression; and reforming the global financial system so that such a crisis never recurs. On the first point, governments have moved quickly to prop up banks. Central banks have slashed interest rates and put in place measures to keep credit flowing to the developing world. Consensus is building for increased government spending. It is more efficient if all countries agree and the moves are co-ordinated – then one man’s higher spending is not frittered away on another’s exports. Yet G20 members need not reach collective agreement for individual states to go ahead.