Perhaps it's their shared love of Midsomer Murders. Or maybe they have been drawn closer together by the realisation that their nations' football teams are not quite the giants they once were. But out of the political stalemate of the EU budget summit has emerged Europe's hottest new item: Camerkel.
In truth, Angela Merkel and David Cameron's new alliance is for pragmatic, mutually beneficial reasons, rather than admiration for the way DCI Barnaby deals with the high murder count in Midsomer. The German Chancellor came to the rescue of Mr Cameron on Friday by showing sympathy for the Prime Minister's plans to slash the cost of Brussels bureaucracy. The talks fell apart when Sweden, the Netherlands, Germany and Britain said the £786bn deal on the table, proposed by the European Council president, Herman Van Rompuy, was not acceptable. But it was Mrs Merkel's backing of Mr Cameron that mattered most.
Diplomats and observers said the new alliance between London and Berlin was "important" and "significant" and, even if it may not last until EU leaders come together again to agree the budget in January and February, it was the most significant thing to emerge at the two-day summit.
Senior German figures believed it was "completely unacceptable" that attempts were made by MrVan Rompuy and José Manuel Barroso, president of the European Commission, to isolate Britain during the talks. Mrs Merkel backed the principle, if not the scale, of the PM's calls for cuts to the EU budget.
In doing so, she distanced herself from the Socialist President of France, François Hollande, who favoured higher spending. While the Franco-German alliance is the most powerful in Europe, relations between the centre-right German Chancellor and the left-wing French President are not the same as they were when Nicolas Sarkozy was at the Elysée.
In turn, Mr Cameron needed backing from fellow EU leaders to show to his audience back home that he was not isolated. He has struggled to hold sway in Europe since becoming Prime Minister, and his relations with Chancellor Merkel were already strained after he ordered the severing of ties between Tory MEPs and those from her party in 2009.
Mrs Merkel's reasons for backing Mr Cameron are, say diplomats, in part related to her desire to be seen as the "saviour of Europe", which would help her in next year's German elections. One observer said: "Merkel will play the card of 'I am the German Chancellor who saved Europe'. She cannot be seen as fighting to save the eurozone at the same time as having a spat with Cameron.
"There is a 19th-century view of the importance of the balance of power – Germany still believes in having the British in Europe as a counter-balance. There is the German philosophy wanting Europe to be a Europe of peace."
German-born Mats Persson, director of Open Europe, an independent think tank calling for reform of the EU, said that on a personal level, the two leaders get on well together, but it was also "important to be seen to be building a bridge". He added: "Britain and Germany have a few interests in common. Paris and Berlin failed to reach a common position. Berlin leaned more towards London. Cameron got a bit of sympathy for administration spending from Germany. A small amount, but it is quite important. Both Germany and Britain are in favour of prudent use of public finances." This week, Open Europe is launching a partnership organisation, Open Europe Berlin, in the German capital – underlining the importance of Berlin-London diplomacy.
The leaders' relationship has been something of a rollercoaster: after the spat over their MEPs, Mr Cameron tried to win the Chancellor over by giving her a box set of Midsomer Murders on her visit to Chequers in 2010. At their first G8 summit together, in June 2010, they shared a beer while Germany hammered England 4-1 in the World Cup.
A month ago, in the run-up to the budget summit, relations were fraught when the two held talks in Downing Street. Some of Mrs Merkel's closest advisers are known to dislike Mr Cameron intensely. So how long can Camerkel last?
An observer said: "At some point patience in Berlin with Britain will run out. The Franco-German alliance remains the most important axis in Europe. This is a temporary alliance. If there is a new political treaty, further down the line, everything will change. The French and Germans will take the view that Britain has to sort itself out."
Blair: 'Britain must stay in EU'
Tony Blair is to mount a staunch defence of Britain's membership of the EU this week, insisting that it is vital to the future economic prosperity of the country.
The former PM, in a speech in London organised by the pro-European group Business for New Europe, will outline why Britain needs to be at the "top table" in summit talks or risk being consigned to the sidelines.
Mr Blair's intervention comes amid growing Euroscepticism in the UK; a poll for The IoS last week showed six out of 10 voters would consider leaving the EU. It will also be seen as a veiled swipe at David Cameron's handling of EU budget negotiations last week. In 2005, Mr Blair chaired negotiations on the EU budget in one summit, while this time EU leaders are forced to reconvene in the New Year.
Mr Blair will highlight figures to show the importance of Europe to Britain, including that 47 per cent of UK exports go to EU states, and that 50 per cent of foreign direct investment to the UK comes from the EU.