Coalitions are unusual in peacetime in this country, which we often forget when we assess how the Government is doing. When pollsters ask focus groups what they think, they do not say how glad they are to see two parties working together for the good of the nation; they say the Government seems divided.
As we approach the halfway point of this parliament, the arrangement between Conservatives and Liberal Democrats seems unhappier than ever. Both leaders are being stalked by challengers capitalising on resentment in each party against the other. Like a couple of saucy secretaries in a Seventies sitcom, Boris Johnson and Vince Cable are turning heads among their parties' members and MPs.
Tory right-wingers who think that David Cameron has conceded too much to the Lib Dems wonder whether Boris would be more of a tax-cutting Eurosceptic as prime minister. (No is the answer.)
Vince meanwhile is in trouble with his leader for showing a bit of left ankle, letting it be known that he has exchanged text messages with Ed Miliband. Also for the interview in July when he said "the worship of youth is subsiding" and "I don't exclude it", when asked about the leadership.
The text messaging prompted a rebuke from Sir Menzies Campbell, Lord Protector and Patron of Nick Clegg, on Friday: "The success of this coalition depends upon everyone who participates in it being a full subscriber." And Cable fed his injured innocence to the news beast on all available channels, saying, "I don't understand the fuss" and that he was in favour of an "adult, mature relationship with people in other parties".
The motives of Boris and Vince are no mystery. Boris wants to be prime minister and knows that the London mayoralty gives him a wonderful chance to show off his way with words without being bound by collective ministerial responsibility. He also knows that, if anything were to happen, it would not be until much closer to the election, when Tory MPs are close enough to see the whites of voters' fury, and then only if opinion polls suggest strongly that the Tories would lose under Cameron but might win under Johnson. Meanwhile, he is having fun.
Vince has a surer path to his party's leadership, although he might have less of a party to lead after the election. Lib Dem support in the polls is around half what it was in the 2010 election, and there is no reason to think that it will rise much by 2015. Clegg is likely to be punished for halving the party's vote: the only question is whether sentence is passed before the next election or after – or whether, like a racing driver about to take a corner too fast, he takes the safety exit to Brussels in 2014. Vince is now positioned ahead of Ed Davey, the Energy and Climate Change Secretary, as the alternative leader with whom Labour could work if a different coalition is called for.
So if either party is to change its leader, it would not be until closer to the election. The coalition will run until 2015 because it is in the interest of neither party to have an earlier election. In the case of the Lib Dems, it is not in their interest to go to the polls at any time in the next 50 years or so, so they might as well put off the reckoning for as long as they can.
Meanwhile, the truth of Benjamin Disraeli's dictum that "England does not love coalitions" is reinforced month by month. Since that quotation has come up, allow me to draw your attention to a superb academic paper about it by Iain McLean, professor of politics at Nuffield College, Oxford, in a journal called Government and Opposition. In it, he explains how a "passing remark" by Disraeli – the Matthew Hancock of his time (Hancock, a new Tory minister in Vince Cable's department, compared himself to Pitt, Disraeli and Churchill in an unguarded interview last week) – "delivered at the end of a stream of coruscating abuse, has been taken by some to be a foundation stone of the British Constitution".
Disraeli himself rose to high office in a coalition of the extremes against the middle, of protectionist Tories and the Irish against the Peelites. When he made this comment in 1852, he was Chancellor in a minority Tory government that was about to fall, to be replaced by a different coalition led by Lord Aberdeen and the Peelites.
McLean argues that the stability of coalitions depends on something else that Disraeli talked about in that speech: the "mild and irresistible influence" of public opinion, which "governs the country". The coalition of extremes in which Disraeli served could not hold because the Peelites were closer to the centre of public opinion. There is a parallel here with the present coalition, between a party of the centre-right and one that, since the Iraq War, has often been to the "left" of Labour. No wonder the Lib Dems are suffering a crisis of identity: they are paying the main price for the coalition's incoherence.
We should perhaps rethink Disraeli's "passing remark". It is not that England does not love coalitions; it does not understand them. It does not see parties working together in what Vince Cable might call an "adult, mature relationship"; it sees ferrets in a sack.