This has been the paradox of the G20. There were many sensible warnings about the risk of excessive ambition, that the summit was seeking too much, too soon, given how many nations were involved, and how early this was for a new US administration with so much on its plate at home. Yet, at the same time and no less legitimately, there was a recognition that whatever could be done would not match up the scale of the global economic crisis. Poverty of ambition would be the great failure. Whatever could be agreed, more would be needed.
So Gordon Brown stood accused of wishing for too much, and for too little, at the same time. The London summit outcome surely validates his efforts, though it will take some time for everybody to fully digest it.
And only the Prime Minister's harshest and most predictable critics will begrudge him the positive reactions - from fellow world leaders and even from the British press - which the substance of the G20 deal merits. The scale of international agreement reflects a shared recognition of the scale and urgency of the crisis. It is also testament to the level of political capital invested in the summit by the Prime Minister in particular, but also to the technocratic quality of the heavy lifting policy work done by the UK government alongside its partners.
The historic meaning of the G20 will be that it reflects a series of global power shifts.
Clearly, the emerging powers have arrived at the top table, after several decades dominated by the global order of 1945: and that will now be increasingly reflected in the major multilateral institutions.
There is a new global approach which is predominantly social democratic. Commitments on the economy, to the developing world and on climate change need to be followed through: it should be clear that serious progressives should be campaigning for the G20 to follow through and do more, not for it to go away. And while one would not want to exaggerate an Anglo-Saxon/continental faultline, but the Obama-Brown alliance saw the content of those disputes shift, as Poul Nyrup Rasmussen's criticisms of European centre-right governments.
And the Obama media briefing was striking for its clear, if undramatic, statement of American interdependence and a commitment to multilateralism.
America is a critical actor and leader on the world stage, and that we shouldn't be embarrassed about that, but that we exercise our leadership best when we are listening; when we recognize that the world is a complicated place and that we are going to have to act in partnership with other countries; when we lead by example; when we show some element of humility and recognize that we may not always have the best answer, but we can always encourage the best answer and support the best answer.
So I think that's the -- that's the approach that we've tried to take in our foreign policy since my administration came in. Now, we come in at extraordinarily challenging times, and yet I actually think that that calls for this type of leadership even more.
All of these are important features of the global politics in 2009 which might have seemed a long way distant even five years ago.
In another way, the summit captured the continuing centrality of the nation state to our new age of multilateralism. National sovereignty matters, as nation states must find common interests to agree, yet the summit shows too how much effective sovereignty often now means a seat at the negotiating table. Europeans will be effective in such fora when we agree among ourselves. (This, as much as their opposition to any fiscal stimulus, is what sets Her Majesty's Opposition in Britain so far adrift from the centre-of-gravity of the new multilateralism).
Attempts to assess the outcome again primarily through the lens of domestic electoral politics will miss the point again. No global summit, however glitzy, however successful, is going to transform domestic opinion polls overnight, or probably have a great impact on this June's election results. The government's first responsibility is to govern. Governing well might bring a political benefit in the end too, and it might not too. But tonight even hardened lobby hacks are acknowledging that the outcome of this summit was about much more than that.