Graeme Archer is a statistician and a former winner of the Orwell Prize for Political Blogging.

It’s nearly Spring, and only 70-odd days till polling day, so this no-longer young man’s thoughts have naturally returned to Oldham. Remember 2010’s Oldham East and Saddleworth by-election? Won by…Labour.

Labour won the seat at the preceding general election too, with a majority of just over 100, with the Liberal Democrats in second place. The Conservative Party was a distant third. In the actual by-election, the combined LibDem and Tory votes outnumbered Labour’s by 923.

When we knew a by-election was to be held, I wrote an unpopular piece for this website, called, unpoetically, An Open Primary Should Select a Coalition Candidate for the Oldham East and Saddleworth By-Election. My point, then, was only partly arithmetic (probably a Lib Dem would win the open primary, and probably most Conservatives would support that Coalition candidate in order to stop Labour) but mostly political: if you govern as a coalition, you should fight elections, too, on that basis.

Instead, both the Conservatives and the Liberal Democrats decided to be purists about tribal loyalty, and chose to make it likely that Labour would win. As, predictably and predicted, turned out to be the case. This was a conscious choice.

I couldn’t get my head around it in 2010.

Still less, in this weirdly goal-free election campaign, can I get my head around it now. No, I haven’t changed my mind about AV. Nor do I suddenly think well of Simon Hughes. I’m not drifting leftward with age, except, maybe, in a Swanson-ite sense (“I am big; it’s the pictures that got small.”)

It’s just, I would argue, one reason for the unreality of the unfolding campaign: this cognitive dissonance which both coalition parties insist upon. “We are proud of our record in government. So don’t, whatever you do, vote for the government.”

Why do we do this to ourselves? I’m no fan of the Lib Dem construct. But this mutually agreed policy, of pretending that everything about Coalition was awful, has not heralded an electoral breakthrough for either party. So it doesn’t even succeed in its own terms.

For the Tories, only Nick Boles, I think, has thought how to widen the centre right tent, proposing a Liberal Party for, well, liberals who would be uncomfortable with some of the guy-ropes in a solidly Tory wigwam.

The disdain for Coalition is not uniquely Conservative. Lib Dem activists and that party’s less appealing MPs continue to protest that they have some distinct ideology that makes them equidistant from both the other parties, as though “Lib Dem” means “half a socialist, and half a believer in freedom, enterprise and the rule of law.” But as Brighton’s Lib Dems discovered, as they were displaced, ward by ward, by the Green party: there’s only so much space on the political map for different ideas to inhabit, whatever labels you stick on them (as the disintegrating Green coalition is now finding out itself, deliciously and ironically).

As has been written so often that my fingers groan at having to type it out again: the Lib Dem entity is itself a coalition, between leftist social democrats who’d be much happier supporting Ed Miliband, Ed Balls, Harriet Harman et al., and classic liberals. I cannot conceive that this latter group are not happier aligned with the movement of Thatcher, Joseph and Willetts than they would be enacting the Miliband agenda.

The task for Conservatives in this parliament should have been to detach those Liberals from their current social democrat cohabitees. We should have love-bombed them, and (cue Shirley Bassey) encouraged history to repeat itself. (First, liberals sit with Tories; then they vote together; then they become one another, to the long-term advantage of both political movements.)

This isn’t about disavowing Conservative ideals, but it is about banishing the sterile pretence that parties exist to give each individual supporter 100 per cent of what those individuals want, or that there’s never been a liberal strand to Tory thinking.

Consider this thought experiment:

One of my heroes in this administration is the LibDem Steve Webb, the minister whose reforms have liberated middle-class middle-aged men like me from the tyranny of the insurance companies’ pension annuity rip-offs. I don’t know which seat Mr Webb represents, and I’m deliberately not going to look it up.

But suppose I lived in it. And suppose the Tory PPC was…UKIPish, of the “nativist” persuasion. (Again, let me emphasise: I don’t know who is Mr Webb’s Tory opponent.) Am I supposed to pretend that I would rather be represented by a Conservative Faragiste, than by the man who saved my retirement? And saved it, moreover, with reforms that are both liberal (it’s your money) and Tory (so we trust you to spend it wisely)?

The whole record of this (excellent) government in welfare reform proves that even staunch social conservatives can work with liberals to achieve policy that benefits everyone. You could call it “one nation” politics.

Has the modern age (Gimme! Gimme! Gimme!) blinded us to the eternal truth of the Rolling Stones? The married couple’s tax allowance and boundary reform were two policies that made me want a Tory government more than ever. That the one was delayed and the other killed off because of coalition enraged me at the time. But look at the sky! It’s still there. Together with the sun, shining down on a government that doesn’t contain any Labour MPs. You can’t always get what you want. But we got what we needed.

The alternative (to institutionalising the liberal-Tory coalition) is where we are now – that liberals and Conservatives work together for a parliament, but then fight the election as though they are sworn enemies. This is ludicrous, as manifest in the wish held by many Tories that the deputy prime minister of the Tory-led government loses his seat to a Labour candidate. “Cognitive dissonance” doesn’t begin to cover this.

Why are the parties so ashamed of one another? The two outcomes I most desire from the May 7 election is that Labour be kept out, and for David Cameron to remain Prime Minister. Were that choice – the Coalition ticket – on the ballot paper on May 7, I think it would win by a landslide.

Instead, both parties insist that coalition is by definition awful, and so, by implication, that another liberal-Tory government would be a failure. Remind me, again: how did the Oldham East and Saddleworth by-election turn out?