That cycle of comeback followed by unforced error, punctuated by bouts of confusion about what he believes, illustrated perfectly the perpetual problem with Cameron. A man who is capable of startling coup de theâtre and moments of bravery, who is comfortable in his own skin and confident in his ability, at other points falls back on sloppy thinking, rooted in a sense of entitlement, dud advice and complacency. It is this above all that makes him infuriating.

Even though his inconsistency and unwillingness to listen to unwelcome advice have riled parts of his party and caused periodic rebellions, the ramshackle approach has got Cameron a long way, through nine years as leader of his party, including four years as Prime Minister.

His record in government contains solid achievements in the field of education reform and changes to the welfare system. The economy is growing strongly, and if critics say it is not the perfect recovery then one must ask if perfection in these matters is really possible. At least, after six years dominated by the crash and its aftermath, there is hope and some confidence is returning.

By offering concessions to his Eurosceptic colleagues — often leaving it until it was almost too late — he has arrived at a position on the EU (renegotiation and then an in-out referendum by 2017) that has held his party together, although for how long remains to be seen.

On the debit side, Cameron has also been prepared to play dangerous games with the constitution, offering his coalition partners the Liberal Democrats all manner of concessions. The cockeyed plan to create an elected House of Lords was only seen off by a rebellion of Tory MPs. Defence — one of the core responsibilities of government that Tories are supposed to take seriously —has also been hacked as the budget for overseas aid has soared. In addition, the tax system has been distorted further by Osborne, with another two million aspirational Britons dragged into paying the higher 40p income tax rate.

It is on this mixed record — with the excitement of the recent European elections out of the way — that Cameron will go to the country next year. In normal circumstances, it would certainly be enough to secure him a majority in his own right. The Labour opposition is struggling badly, with a leader who has failed to convince the voters that he is prime ministerial material. Ed Miliband's early musings on economic concentrations of power and monopolies in the energy market and banking were interesting, but his proposed solutions have invariably involved traditional left-wing price-fixing, high taxes and state micro-management.

If it were only a matter of beating the struggling Miliband, the Tories would be in business. But these are not normal circumstances. The traditional British party system appears to be breaking down, with neither of the two major parties seemingly capable of getting close to even 40 per cent of the vote.

UKIP has also emerged to pose an existential threat to the Tories. Even though support for the populist party will subside by the time of the next Westminster election, because some of its voters are using UKIP as a vehicle for protest, it will surely not fall back to the 3.1 per cent it scored at the last general election. This means there a danger of a semi-permanent split on the right in Britain in which it becomes impossible for a single party to assemble a winning coalition of conservative-inclined voters.