Clegg's seismic impact

For the time being, the necessary response is to assume this has been a "game-changing" event and to consider its possible implications. Today we publish the results of opinion polls conducted for Scotland on Sunday and analysis from expert Professor John Curtice, of Strathclyde University. They show that in Scotland too the Liberal Democrats have enjoyed a post-debate "bounce", increasing their support by five points. When that is translated into a projection of Westminster seats, however, the outcome could not be less sensational. Compared with the result of the 2005 general election, the Liberal Democrats would remain static, at 11 seats; so would the other parties, except that Labour would lose one seat to the SNP. That is hardly a seismic change.

In contrast, the projection for Holyrood shows a major transformation resulting from the Lib Dem surge. The Liberal Democrats would gain eight seats, rising to a total of 24. Labour would benefit almost as much, gaining seven seats for a total of 53. And the catastrophic losers would be the SNP, forfeiting 13 seats and their governance of Scotland, for a reduced total of 34. On the face of it, that projection is highly dramatic, especially for Alex Salmond. But here, too, there is a deflating caveat: the Holyrood elections are not due until next year, affording considerable opportunity for the Clegg factor to diminish. And it is now an accepted political fact that the Scottish electorate are very capable of voting different ways in different elections.

However the Clegg factor might not diminish if he is in government next year, presumably in a Labour/Liberal Democrat coalition, or conceivably dictating the agenda on an issue-by-issue basis without entering into a formal pact. If any such event were to occur, the Liberal Democrats' non-negotiable demand, even from a Tory minority government, would be a radical change in the electoral system. To understand the significance of that, there could be no more effective illustration than our polls today. At Westminster, still governed by the traditional first-past-the-post system, a significant Lib Dem surge produces no change in the party's parliamentary representation and only one seat would change hands among the other parties. At Holyrood, on the other hand, with its proportional representation system, a government falls and there is a major realignment.

It has to be recognised that a switch to proportional representation at Westminster could end single-party government for ever. That prospect will neither thrill nor appal Scots as it may do many English voters: we have lived with coalition and minority governments under devolution. At United Kingdom level, however, a hung parliament after May could present major problems. If politicians started horse-trading and indulging in brinkmanship, the markets would take fright, with catastrophic consequences for the economy.

Yet there could be advantages. A national government, sinking political differences, could promote economic recovery if politicians quickly and sensibly got on with the task at hand. The experience of minority government at Holyrood shows that controversial legislation cannot be passed (which many people would think is no bad thing), but it is possible to govern with stability. All of this opens up areas of fascinating speculation; but, as we have said, even just a week from today it could all be academic.