Mary Ann Sieghart: Cameron is backing the old politics

If Alternative Vote gets through, it would leave the Tory leader on the wrong side of the argument, aligned with the wrong people, with his image as a moderniser tainted

Think back to the start of the year and ask yourself, "How fed up was I then with politics?" I bet – on a scale of nought to 10 – you would have scored more than eight. But what about now? If you're tribally Labour, the answer might still be pretty high. But for most of the rest of us, our earlier fury with politicians and the way they do politics has been replaced by a slightly surprised contentment.

That's not to say that voters necessarily agree ideologically with the coalition Government. But what they do like is the grown-up way in which the Conservative and Liberal Democrat leadership has gone about forming a coalition and overcoming their differences in Government.

This "new politics" has drained much of the poison out of the relationship between our rulers and the ruled. So far, David Cameron has cleverly positioned himself at the "newest" end of the spectrum. He turned down both minority government and a loose pact with the Lib Dems in favour of a full coalition, even though it involved putting nearly half the Lib Dem parliamentary party behind ministerial desks. His latest gesture to the new politics is to allow the Lib Dems their greatest prize: a referendum on voting reform, to be announced this week and held next May.

It's still only a consolation prize for Nick Clegg. The Alternative Vote (AV) system is barely more proportional than the existing first-past-the-post one, though it should give the Lib Dems about 20 more seats. In return, he has had to agree to Tory demands to cut the number of MPs by 10 per cent and equalise the size of constituencies, both of which may harm Lib Dem interests.

But what is more surprising is that Cameron has confirmed he is going to campaign for a "no" vote in the referendum. And that will send him sliding right back down the scale towards the old politics again, propping up the first-past-the-post system alongside such troglodytes as John Prescott and John Redwood. Is that really how he wants to be seen?

Who sits on which side of a referendum campaign matters, particularly when the question is a complex one. Many voters don't want to have to learn the intricacies of electoral reform; they just want to join a club of supporters with whom they feel comfortable.

In the late 1990s, I helped to start the "no" campaign against Britain joining the euro. We believed – presciently, as it turned out – that tying disparate economies together with the same interest rate and exchange rate was a very bad idea that could lead to disaster. We were not anti-EU, just anti-euro.

The trouble was that, in those days, the most vocal opponents of the euro were seen as swivel-eyed, anti-European, right-wing xenophobes, while the euro was being sold as modern, progressive and pro-European. Yet there were loads of voters on the centre and left who were suspicious of the project but reluctant to say so for fear of the company they would keep. So what we did was to bring together a strong group of lefties, greens, trade unionists, centrists and wet Tories, as well as former senior diplomats, business people, economists and academics, to legitimise these voters in the views they privately held.

We also recruited people from well outside politics to our cause, such as Bob Geldof, Rik Mayall and Harry Enfield. It worked. Despite Tony Blair's best entreaties and his stellar popularity (this was still his first term), British people kept telling pollsters that they would oppose the euro by a margin of two to one.

So the kind of people on each side of the AV debate will matter too. The "yes to AV" campaign will boast – almost certainly – a new, young Labour leader, as well as that nice Nick Clegg. They will be opposed by old-style, clunky politicians on the right wing of the Tory party and the left wing of the Labour party – and David Cameron.

The "yes" campaign will be able to tell people that, with AV, their vote will count. They will be able to put their favourite party first, instead of having to vote tactically. And even if their first-choice candidate doesn't win, their second preference will still make a difference. All this can be achieved without losing the link between MPs and their constituents. What's not to like?

The "no" campaign will have a much harder case to make. Before the election, it could have claimed that AV makes hung parliaments more likely and that coalitions are desperately unstable and unBritish. Now? That doesn't sound very convincing.

Normally, a "no" campaign can bank on voters using a referendum as an opportunity to punish their rulers. This time, the Government may well be unpopular by next May, but because the Lib Dems will be in favour of AV and the Tories broadly against, voters won't be able to send a clear message. And normally, voters take a lot of persuading not to stick with the status quo in a referendum. But this time, there is so much impetus for a change in the way that we do politics that a modest reform such as AV may well get through.

Where would that leave David Cameron? On the wrong side of the argument, aligned with the wrong set of people, with his image as a moderniser tainted. And it's not even as if a move to AV would necessarily damage the Tory party electorally. When the Electoral Reform Society tried to calculate what the 2010 election result would have been with AV, it's true that the Conservatives were 26 seats short of where they are now. But by the next election, things could be very different.

Then the assumption was that the second preferences of Lib Dem voters would split roughly evenly between Labour and Conservatives. Now many left-leaning Lib Dem voters have already deserted the party. Those who remain are broadly well-disposed to the coalition and are more likely to give their second preferences to the Tory candidate. With Labour bashing the Lib Dems at every opportunity, this is only likely to increase.

The Australian experience with AV has shown that 90 per cent of voters follow their party's recommendation in deciding which candidate to put second on the ballot paper. If Tories recommend the Lib Dems and vice versa in each constituency, each will gain at the expense of Labour.

And if, after the next election, there are more Lib Dem MPs and a hung Parliament, Clegg's party is surely more likely to stay with the party with which it has been in coalition than join up with the party that has been denouncing it for the past few years.

One cabinet minister admitted to me yesterday that Cameron may not even want a "no" vote. "But he has to campaign for one because the Conservative Party is so strongly in favour of the status quo and, given how far he's taken it, he couldn't go any further." Expect, instead, to see a few of the cabinet ministers closest to Cameron being given licence to support the "yes" campaign.

But what does that tell us about the Conservative leader? He could have stuck his neck out and joined the "yes" camp. He could have remained studiedly neutral. Instead he has given in to the most unreconstructed wing of his party – giving Labour a chance to say: "Same old Tories" all over again.

sieghart@journalist.com