The Year in Review: The Coalition

Nick and Dave – the wedding of the year

The high point came at the beginning, and was always going to be impossible to match. Fittingly, the two partners displayed their mutual affection in a rose garden – at the back of 10 Downing Street.

The personal chemistry between David Cameron and Nick Clegg couldn't have been scripted. A joint press conference that could have become a spin doctor's nightmare was an undoubted triumph. In a country that had not seen a coalition for 65 years, many were sceptical that this marriage of convenience would last. But the public seemed to like it, and it soon became clear that the Nick and Dave double act was about much more than a one-off star performance.

Most Conservative ministers bonded with the Liberal Democrats assigned to their departments. As the days and weeks went by, it seemed that the talk of a "new politics" meant more than just the usual rhetoric.

Six months into the marriage, the Coalition Government had for the most part been a remarkably professional, cohesive, disciplined and united administration – much more so than many had imagined back in the rose garden in May. Few doubted that the rock on which it was built was the personal bond between the two leaders. Potential disputes between the Coalition parties were quietly defused at the very top. When rows became public they were often "blue on blue" – one Tory versus another. On important Cabinet committees, there was often an alliance between Liberal Democrats and liberal Conservatives on the one hand, and Tory traditionalists on the other.

The minefield of the Government-wide spending review in October was negotiated by the two leaders and two close allies. The "quad", as it became known in Whitehall, became a powerful inner cabinet – with Mr Cameron joined by the Chancellor George Osborne and Mr Clegg by Danny Alexander, the Chief Treasury Secretary.

This "marriage" was not a figment of the media's imagination. When the Liberal Democrats held an "away day" last month (November) to learn lessons from Liberal politicians on the Continent who had served in coalitions, they were advised on how to treat their relationship in strictly personal terms: "Everything you need to know about coalition politics you already know from your marriage."

However, the Cameron-Clegg love-in has its limits. They may have played tennis together but they judge that the public want it to be business, not personal. "I don't think what the country wants is for us to become best mates. It's about, can we sort stuff together?" Mr Clegg told The Independent on Sunday.

After seven months, the marriage hit a rough patch. Both partners knew it was coming. The decision to raise university tuition fees was bound to cause grief. But it fell disproportionately on Mr Clegg because of his party's spectacular U-turn on the issue. His effigy was burned by the student protesters, while our Telfon-like Prime Minister popped up on TV to condemn the violence on the demos, safely on the side of most of the public (unlike poor old Cleggy). It may not have been deliberate, but it happened, and it left some Liberal Democrats wondering whether the relationship was a bit one-sided.

Allies insist that Dave genuinely worries about his friend Nick. On the Tory backbenches, there are quips about "Operation Rescue Clegg", and grumbling about too many concessions to him on policy. It was David Davis, the former shadow Home Secretary, who coined the critics' most memorable phrase, branding the relationship the "brokeback coalition" after the film about two gay cowboys.

Mr Cameron would be aghast at the prospect of losing the ultra-loyal Mr Clegg, who is seen as the glue that holds the Coalition together. one minister said: "Cameron is the most important person in the Government but Clegg is the most indispensable." Mr Clegg battled on with a slimline staff because he did not want to build up an alternative operation to Mr Cameron, provoking chatter on the Whitehall network that the Deputy Prime Minister was swamped.

Another Liberal Democrat leader might not adopt Mr Clegg's "in for a penny, in for a pound" approach. He is convinced that his party cannot stand aside from the most painful decisions, notably on spending cuts, and must share ownership if it is to have any chance of getting some credit when the economic corner is turned. Mr Clegg takes heart from his party's private polls, which suggest that voters' pre-election fears about hung parliaments and coalitions had been allayed.

Yet as the year drew to a close, there was a growing feeling at Westminster that the marriage is more between two leaders than two parties. Most Liberal Democrat backbenchers voted against the hike in tuition fees. Although Mr Clegg hopes the fight with his party was a one-off, it left some scars.

The two leaders tried to draw a line under the controversy by holding a second joint press conference just before Christmas. But the timing was unfortunate. It was dominated by the Business Secretary Vince Cable's critical remarks about the Coalition to undercover reporters. The Prime Minister and his deputy negotiated the minefield and the personal chemistry between them was still good. But they got little credit as more explosive comments by Mr Cable about Rupert Murdoch were leaked during their press conference. He kept his Cabinet post, minus media regulation, but at a cost to him and both leaders. It seemed as if Mr Clegg needed the most prominent left-leaning Liberal Democrat inside the tent and that Mr Cameron was powerless to sack him. It was a messy end to the year, and a reminder that, however strong their personal relationship, the two partners could not escape the stresses and strains inherent in any coalition.

There were growing Tory fears that Mr Cameron wants the relationship to last beyond 2015 and an anti-Labour pact at the general election. This prompted a fightback by Tory traditionalists and the launch of Mainstream Conservativism, an alternative to Liberal Conservatism, by Tim Montgomerie, editor of the ConservativeHome website. Its survey of Tory members found that, while 75 per cent approve of the Coalition at the end of 2010 (20 per cent do not), some 79 per cent want the Tories to govern on their own after the next election (only 16 per cent want to extend the Coalition).

A plan to prolong the Coalition would offer the Tories an insurance policy if they failed to win an overall majority. If they could govern alone, Mr Cameron would come under strong pressure from his own party to do so, and Mr Clegg could be left waiting at the church.

The recent tensions have fuelled speculation that the Coalition might not last until the 2015 election or that the Liberal Democrats will split, with a rump of Cleggites joining the Conservatives. This seems unlikely: if other Liberal Democrats walked away, they would have nowhere to go and would face an early election in which their party could be massacred. "The relationship is doomed to last," one Cabinet minister said.

For how long? The timing of the divorce will probably be settled not by Mr Cameron or Mr Clegg, but by the voters.