John Curtice: Why the debate on PR is only just beginning

How can public opinion be so contradictory? Sixty-two per cent of people, a record level, say they back the introduction of proportional representation. But at the same time almost the same percentage, 57, feels that it was right that Labour secured an overall majority on just 36 per cent of the vote because the party did win more votes than anyone else.

The answer is relatively straightforward. We have long wanted the best of both worlds in electoral systems.

We find it difficult to disagree that seats should be handed out "fairly", and what could be more fair than allocating seats in at least reasonable proportion to votes won? So when pollsters ask us whether seats should be allocated more proportionately they invariably get a positive response.

On the other hand, we also find it difficult to dispute the argument that government should be "strong" or "effective". So, when faced with propositions that we should keep the current system to produce (it is said) that result, we tend also to agree.

Of course proponents of proportional representation would dispute the notion that single party governments are necessarily more effective than the coalition governments that are often the product of proportional representation.

They would point, for example, to the experience of Scotland, where the existence of a coalition over the past five years has hardly produced a murmur.

But the winner-take-all mentality is evidently still has a strong hold on the British public even though the winner now only has 36 per cent of the vote, although intriguingly it appears to have rather less hold amongst older voters, who perhaps remember elections between 1945 and 1970 when the winning party usually took more than 45 per cent of the vote

So while the result of the election does seem to have reignited concern about the fairness of the electoral system, advocates of change should not assume that the fact that Labour won an overall majority on well under 40 per cent of the vote has necessarily shaken the public's regard for single party government.

Perhaps that confidence would have been shaken rather more if Labour had not just won a relatively low share of the vote but had actually won fewer votes than the Conservatives yet still secured a majority, But as it happened that only in England was this possibility actually realised on 5 May.

But once ignited, debates can have an effect of their own. Our willingness to give contradictory responses to survey questions about electoral systems suggests that relatively few of us have thought through the trade-offs involved the choice of an electoral system or have firm views on the subject.

If the result of the election has now started a new debate on the subject, it is a debate that has the potential to persuade. What is not clear is which will be the more powerful argument, "fairness" or "effectiveness".

John Curtice is Professor of Politics, Strathclyde University