John Rentoul: Cameron fancies a long stay at No 10

The New Politics, part 94. Two parties form a coalition and one of their first Bills is to enact a policy which neither party supports, but which is the official policy of the third, the Labour opposition. Thus there will be a referendum next May on a change to a voting system that would allow people to number candidates in order of preference.

This is the policy, called the alternative vote for no good reason, on which the Labour Party fought the election. The Liberal Democrats were committed in their manifesto to a proportional system, which the alternative vote is not. It does not seek to match each party's share of the vote with its number of MPs. And the Conservatives declared their very conservative dedication to keeping the X-voting system as it is.

This is all marvellous, of course, even if you are not a lover of paradoxes or a reveller in politics when it most resembles triangular chess, because the alternative vote is plainly a superior method of electing MPs to the present one. And I think that the change is – just – likely to happen.

The usual argument for the alternative vote is that it would ensure that each MP has the support of a majority of the voters in his or her constituency; whereas most of today's MPs were elected with less than 50 per cent of the vote. This seems to put it the wrong way round, looking at it from the point of view of the elected rather than the elector. Surely reform must be sold a means of empowering the voter.

As a voter I want to express more than one preference. If my first choice is not elected, I would still like to have a say in the outcome. I believe I am subtle enough to be able to distinguish and choose between any pair of candidates on the ballot paper, and therefore to rank the whole lot in order. Before we arrive at this slightly preferable, multiple-choice system, however, there are obstacles to clear.

First, the Referendum Bill has to pass through the House of Commons; then the people have to vote yes. Finally, the legislation implementing the change has to be passed, and it is possible that the coalition might fall in the interim, as the Labour government did in 1931, while a Bill to introduce the alternative vote was being debated. (A debate that included such gems as this in Hansard from Sir Hilton Young: "It is easy now to see that the number of votes polled by A, B and C respectively at the first scrutiny will be N-b+c, N-c+a, N-a+b." [Hon Members: "Agreed!"]).

The first obstacle is easiest. The two parties that do not agree with the alternative vote are bound by a coalition programme that says, bluntly: "We will whip both Parliamentary parties in both Houses to support a simple majority referendum on the Alternative Vote." Note that the wording precludes what is known as a "Cunningham amendment", after the rogue Labour MP George Cunningham, who spiked the 1979 referendum on Scottish devolution by requiring a yes vote of at least 40 per cent of the entire electorate. Even if Labour discipline breaks down, the Bill will go through.

But the growing unease in the Labour Party tells an important story. Contrary to the party's usual lurch in opposition into a dalliance with proportional representation, the new politics is likely to drive Labour in the opposite direction, on the grounds that PR equals coalition government, which is what we've got and don't like. On this, Andy Burnham, who said that electoral reform was "a kind of fringe pursuit for Guardian-reading classes", may be better at telling the party what it wants to hear than Ed Miliband. One shadow cabinet member told me that the younger Miliband had based his campaign on the "insidious" message to the party that "everything that you ever found difficult was actually morally wrong". But by promising to lead Labour's yes campaign in the referendum he may have misjudged the party's mood.

And it is winning the referendum that is the hard part. That is why David Cameron and Nick Clegg had no problem agreeing to hold it in May, and why I do not believe suggestions that either of them wanted to delay. It won't be possible to win after the honeymoon when the cuts begin to bite. And Cameron is in the curious position of wanting a yes vote, despite being a defender of the first-past-the-post system.

Do not pay too much attention to last week's briefing by No 10 officials that the Prime Minister's position has not changed. As Paul Goodman, the former Tory MP, reported, Cameron "won't be in the front line" of the No campaign. I understand that the Conservative Party will not take a formal position in the referendum campaign, although most of its MPs and grassroots members will be opposed.

The underlying dynamic is that the Liberal Democrats believe that the alternative vote is in their party's interest. It is not their first preference, but it is better than nothing. In the long run, they may be wrong about that, but, at the next election, it will save them some seats. And, as long as they believe it, it is in Cameron's interest to give it to them. If the referendum is lost, the glue that holds the coalition together will weaken.

This is where I think that Cameron is misunderstood. It seems to be generally assumed that, for him, the coalition is flag of convenience, hoisted to help navigate out of the tricky situation produced by the election.

I think not. I think he sees it as a chance for a permanent change in favour of liberal conservatism, a label he has always been happy to apply to himself. The coalition is not merely an expedient to get him through to the next election, when the Tories can try again to win outright. Even if they did, he would, I suspect, want to keep the Liberal Democrats on board. He knows how the alternative vote works in Australia, the only country where it is used. There, the Liberal-National coalition is, in effect, a single party in a two-party system. One that has been in power for 40 of the 65 years since the Second World War.

John Rentoul blogs at: independent.co.uk/jrentoul