A fountain playing in the background, Mr Prodi led his team out on to the sunlit lawn at 12.30pm to proclaim a fresh start for Europe. This being the EU, it was not just a question of a few words, there was the inevitable 60-sheet folder of documentation to back it up.
Launching a new code of conduct, Mr Prodi outlined the rules under which his new, squeaky-clean team plans to erase the sleazy image of the European Commission which resigned in disgrace in March. There will be no trips on Concorde or "air taxis" without prior permission of the Commission's president, and there will have to be a good reason to hire a suite when staying in a hotel.
Stern rules will prevent conflicts of interest, and commissioners face a year-long "cooling- off" period after leaving office, during which any private sector job offer will be scrutinised. And spouses' professional activities will have to be declared. More radically, the 19 commissioners will have to sit through their weekly meetings until they end, and will need permission to be absent.
Much of the code is designed to render impossible a repeat of the latest public relations fiasco - the defection of Martin Bangemann, the commissioner in charge of telecommunications policy, to the board of a Spanish telecoms giant on a reported salary of pounds 700,000. But Mr Prodi knows the importance of a new beginning, and promised that `teamwork, transparency, efficiency and accountability" are "the spirit of Aartselaar". Each commissioner, he added, should be a "big star in his or her policy area".
The business of agreeing most of the draft code of conduct was undeniably important, but inside the four-star Kasteel Solhof hotel, the new team spent more time indulging in what one official described as a "bonding, tree-hugging session". Former rivals and enemies chatted amiably for the cameras: if you closed your eyes, it was sometimes difficult to tell whether you were listening to Neil Kinnock, the incoming vice-president in charge of internal reform, or Chris Patten, the Commission's new external relations supremo.
These two had harsh things to say about each other in the British general election of 1992, when Mr Kinnock was Labour leader and Mr Patten Conservative Party chairman. At one point Mr Patten said Mr Kinnock did not "give a hang for the truth" and had disqualified himself "from the trust and the respect which those who try for the highest office in the country seek to earn"; Mr Kinnock said the integrity of Mr Patten's campaign was "nil".
Yesterday Mr Patten revealed that Mr Kinnock had sent him a "charming letter" congratulating him on his appointment, and that the two men had lunch together. As for 1992, he added, it was "a long time ago for both of us and set us out on political paths which have brought us... to the same place at the same time."
Mr Kinnock said that given the situation it would have been "daft" if harsh words had not been spoken, but it was now clear that they would "work together as good colleagues over the next five years".
And they agree too on the need for reform, Mr Kinnock arguing that "there is widespread support for, and understanding of, the fact that a 42-year- old institution needs change".
Others were on their best behaviour too, including Gunter Verheugen, Germany's prospective commissioner for enlargement, who only last month attacked Mr Prodi in public over the way he was picking his team. Pascal Lamy, the balding former aide to Jacques Delors, and France's incoming trade commissioner, chatted amicably to Mr Patten, despite speculation that their policy portfolios could bring them into conflict.
And Frits Bolkenstein, the Dutchman destined to control the internal market, belied his reputation as a maverick. Mr Bolkenstein was the person Mr Prodi came closest to vetoing before the Dutchman gave a commitment to be a team player. Asked whether he would now curb his outspoken, quasi- sceptical statements about the EU, Mr Bolkenstein responded in an uncharacteristically diplomatic way. "Excuse me," he said. "It's warm and I'm thirsty.'
Cocktails were being served on the balcony, and a slap-up lunch of sole, salmon and lamb, followed by fruit sorbet, was waiting. Even under a new reforming Commission president, some things are unlikely to change.