European Commission president Jean-Claude Juncker gave David Cameron a high-five as they met in Brussels this morning, in an apparent sign that he is not harbouring a grudge over the Prime Minister's failed attempt to block him from getting the EU's top job.
The pair met over breakfast for potentially awkward talks just weeks after Mr Cameron's very public bid to stop the appointment of a man he saw as a roadblock to reform in the European Union.
But Mr Juncker was all smiles as he greeted the PM, who was defeated 26-2 by fellow EU leaders in a vote on his appointment. Mr Cameron has made clear he is ready to work with the new Commission president, though Downing Street stressed it was Mr Juncker who initiated the US-style hand-slap.
"I think that's how Mr Juncker greets quite a few people," said the Prime Minister's official spokesman. "They have known each other for quite a while."
Journalists were not allowed to witness the event, but a photo of the celebratory gesture was distributed by the European Commission shortly after their hour-long meeting, which Downing Street characterised as "substantive, constructive and amicable".
Mr Cameron used the meeting to lobby for Lord Hill of Oareford, his nominee for Britain's place on the Commission, to be handed a key economic portfolio in Mr Juncker's team.
Mr Juncker, a fixture in EU politics for decades and architect of the eurozone, has insisted that descriptions of him as an arch-federalist are overblown.
He has also stressed he is not in principle opposed to the UK repatriating some powers from Brussels - a key demand of Mr Cameron in the run-up to an in/out referendum mooted for 2017.
However, he has said the free movement of labour within the union is not up for grabs, and risked the wrath of Eurosceptics by lavishing praise on one of their hate figures - former commission head Jacques Delors.
Downing Street said that Mr Cameron and Mr Juncker spent 40 minutes discussing the challenges facing the EU over the next five years, before being joined by Lord Hill.
"The Prime Minister set out his vision for reform of the EU and the UK's relationship with it," said Mr Cameron's spokesman. "Mr Juncker reiterated his commitment, set out in his manifesto, to work with Britain and the other member states to address the concerns of the UK over the next few years."
The spokesman said that Mr Cameron had "underlined his preference for securing an economic portfolio that would enable the British Commissioner to play a pivotal role tackling Europe's lack of competitiveness".
Mr Cameron's spokesman stressed that the PM's opposition to Mr Juncker's presidency was always based on "arguments around principles and priorities and never anything else".
He added: "The PM has said very clearly that we will of course be working with all members of the European Commission to secure Britain's national interest."
Mr Cameron's surprise decision to put Lord Hill forward to represent Britain has been branded a "shambles" after the peer had to sell shares in a lobbying firm to avoid criticism over conflicts of interest.
He acted to head off concerns over his significant holding in £140 million global public affairs company Huntsworth, which operates in Brussels.
MEPs had warned that they would be looking closely at the interest in deciding whether to confirm his appointment.
President of the European Parliament Martin Schulz also suggested that he could be rejected for being too Eurosceptic - although he later backtracked and insisted he would be treated fairly at confirmation hearings.
Number 10 pointed out that the European Parliament has the opportunity to approve or reject a new commission "as a whole, as a slate, not as individuals".
Lord Hill told journalists in Brussels that he would not view himself as a Eurosceptic.
"I'm not a great one for looking for names or badges or boxes," he said.
Lord Hill previously replied "non, non, non" when asked if he wanted the EU job - but said last night: "I am not a reluctant conscript. It is true that I loved my time at the House of Lords, which is a fantastic institution, full of wonderful people.
"The fact is, having thought about the importance of this job, the pivotal role that it will play, the crucial time in the history of the European Union and also of Britain, it is a fantastic opportunity to be involved and I would be mad not to do it."
EU leaders last night put off decisions on commissioners and portfolios for a few weeks, with an impasse between Germany and Italy being blamed.
Each of the 28 member states nominates someone to serve in a post for a four-year term, with Luxembourg's spot already taken up by Mr Juncker.
Britain's current commissioner, Baroness Ashton, has a senior role as High Representative, which means that brief will go elsewhere this time round.
The summit also failed to agree a president of the European Council to succeed Herman Van Rompuy - a position for which Danish PM Helle Thorning-Schmidt, wife of Neil Kinnock's son Stephen, is thought to be in the running.