The guest list is impressive. Headed by Tony Blair and Bill Clinton, it will bear the standard of the Third Way. Not that anyone uses the term any more. So very 1990s. The centre-left think-in, the Progressive Governance Conference, from 11-13 July, will struggle to demonstrate that it is both modern and relevant. Clinton's time has been and gone - hope turning to disappointment turning to reappraisal and belated appreciation. Will the same apply to Blair?
Time was, at these international gatherings, when the British Prime Minister was the talismanic figure. He would charge around Europe reinventing social democracy, globalisation and the market as he went along. That hubris is in the past. There are still elements of his project that some Europeans look up to, such as welfare-to-work. On public service reform, Blair has failed to convince. On questions of the social market and employment protection, many countries beg to differ. On the future of Europe, he is no longer given the benefit of the doubt.
Looming over the glittering proceedings is Iraq. The failure of diplomacy that led to the war haunts Blair's relations with much of the world. It shattered his dream of projecting global power and influence from Downing Street. It destroyed many people's hopes for international institutions. It removed any illusions about the international community's ability to control the only superpower.
Still, it says something for the pulling power of Blair and Peter Mandelson, the conference organiser, that they have attracted such a cast list for their talks. Old Europe will be there in strength, led by Gerhard Schroder. New Europe brings the prime ministers of Poland, Romania and Hungary. For the Americas, there will be Canada's Jean Chretien and Ricardo Lagos of Chile, whose support in the run-up to war Blair so assiduously and vainly courted. Most intriguingly, the final symposium includes Thabo Mbeki of South Africa and Brazil's Lula da Silva, in whom so many hopes are vested.
The ghost at the banquet will be George W Bush. The real task for the leaders of the centre left is not so much to produce new policies, but to marry their world-views to the neoconservative doctrines of pre-emption and US primacy. People around Blair now privately admit that they mortgaged too much in their desperate attempts to influence Bush.
The Prime Minister himself might spend the summer thinking through these dilemmas, but - preoccupied as he has been in accounting for the lack of weapons of mass destruction - he has shown no signs of doing it so far. It is "in the very nature of the progressive left", Blair writes in his paper for the conference, to be optimistic. "If we did not have the confidence that the world could be changed for the better, there would have been little point in us getting involved in politics at all." His is, as ever, a curious mix of big-picture pessimism wrapped up in rhetorical optimism - the school of "whatever you think of us, we're better than the alternative".
Other contributions provide a more candid assessment of the problems. Mbeki asks: "Do the progressive politicians have the necessary courage? They need it because they have to present the reality, boldly and frankly, that it is impossible to solve the problem of global poverty solely through reliance on 'the market'."
Javier Solana, the European Union's foreign affairs chief, reminds Bush that Europe is not an appendage of US foreign policy: "The Alliance should determine the mission and not vice versa. The alternative is to pick partners, like tools from a box. Most of us would prefer to be considered an 'ally' or a 'partner' rather than a tool." He writes of the short-sightedness of those who equate commitment to enforcing international law with defence spending. "How much additional security does an aircraft carrier bring? Is it more or less than spending the equivalent amount of money on peacekeeping or the reconstruction of failed states?"
Some of the most interesting thinking on these issues of power and its use comes from the International Crisis Group. Comprising a number of former international statesmen, the group published its first report, The Responsibility to Protect, in December 2001, setting out six principles for military intervention. Gareth Evans, the group's president and a former foreign minister of Australia, reminds the left of its "visceral discomfort" with the use of military force. Citing Rwanda as the prime example, he argues that "in some circumstances military intervention is not merely defensible, it is a compelling obligation". He hedges his bets on Iraq, but makes clear that the responsibility to protect "implies not just intervention but a whole continuum of obligations - prevention, reaction and rebuilding".
Blair has not been shy in using force. Five conflicts in six years will take some beating. He has shown that he can do war. But other leaders want to know: can he do peace?