A rough ride will be Nick Clegg's reward for widening debate

FEW can complain now that the General Election is dull and boring. The first televised debate between the main party leaders drew an impressive audience of 9.9 million. It brought the Liberal Democrat Nick Clegg to widespread public notice. Judging by early viewer polls, he was pronounced the clear winner. That, in turn, makes the election result even more uncertain and difficult to call, but it is broadly judged to have made a hung parliament more likely.

Whether this debate was, as Lib Dem supporters believe, a game-changer depends on whether the favourable mark made by Mr Clegg translates into extra voting support. Initial indications suggest that it has done so on a significant scale. But there are more debates to come, and it is likely now that Labour and the Conservatives will subject the Lib Dem manifesto to the most intense scrutiny and criticism.

Here in Scotland, the debate had considerably less relevance, as many of the issues raised, such as health and education, are devolved to the Scottish Parliament. The SNP feels understandably embittered that its political rivals enjoyed an unfair advantage in establishing themselves before an audience of millions. And it has left Alex Salmond looking marginalised. But given the widespread interest, not to have shown the programme in Scotland would have been self-defeating. The SNP, too, is likely to step up its attacks on the Lib Dems in the approach to the debates next week where the SNP will be included.

It is the Conservatives who have most to fear from the complex dynamics of "the Clegg effect". The Tories have been counting on winning a swath of Lib Dem seats on the south and south-west coast of England to gain the overall majority needed to form a government.

That may be more difficult now. When the Lib Dems do well, they usually do so at the expense of the Conservatives rather than Labour, hence making it even harder for the Conservatives to get a majority. And Tory marginals could be more vulnerable. Of the Lib Dems' top 20 target seats (ie, the extra seats they will win with the narrowest swing from other parties), 14 are held by the Conservatives and only 6 are held by Labour. If the Lib Dems gain seats, it will at least partly come at the expense of the Conservatives.

But if the Conservatives have to take the Lib Dems head-on, what of Labour? Gordon Brown made clear several times in the debate that he agreed with the Lib Dem leader in what many saw as a calculated attempt to secure his support in the event of a hung parliament. That strategy may now have to be revised.

Overall, the first political leaders' TV debate has sharpened, rather than dampened, interest in the election campaign. It will almost certainly lead to a more abrasive scrutiny of the Lib Dem proposals. Next week's debate could see an altogether rougher ride for Mr Clegg. There will be a wider and more vigorous debate overall, now that the leader of the third party has appeared and performed as an equal to the other two.

And that, given the high stakes involved, is no bad thing.