Barack Obama, the US President, hailed the deal as a "turning point" for the global economy which would put it on the path to recovery.
"Today's decisions, of course, will not immediately solve the crisis. But we have begun the process by which it will be solved," Mr Brown said. "I think a new world order is emerging with the foundation of a new progressive era of international co- operation,"
The success was echoed by Mr Obama. "By any measure the London summit was historic," he said. "It was historic because of the size and the scope of the challenges that we face and because of the timeliness and magnitude of our response."
April 2 - G20 leaders seal $1tn global deal
Article: One World Government
President Barack Obama said as much when he acknowledged that the 'Washington consensus' of unfettered globalisation and deregulation was now outmoded, and called for a more balanced approach to regulating markets rather than letting them run free. And it is the shift in the US position, which was previously the strongest opponent of international regulation, that has opened the way for a much broader attempt to regulate the financial sector.
And in the new Financial Stability Board, which will now incorporate all G20 members, there is the potential for a powerful new global financial regulator.
Even more significant is the increased power given to the international financial institutions, the World Bank and the International Monetary Fund, who have been subcontracted by the G20 to monitor and run many of their policies.
Mr Strauss Kahn said that he believed that the G20 was shaping up as the board of governors for the world economy, and said he favoured an even bigger grouping to give more representation to poor countries. It may be that after the crisis is over, the G20 disbands as a group. But given the belief by governments on both sides of the Atlantic that global cooperation is now essential for economic growth, the likelihood is that it will carry on and attempt to strengthen its role.
With fits and starts, the world may be moving to a recognition that as the economy has become global, the power of governments can only be effective if they too become more international in scope.