Leading article: Hurrah for democracy!

Who would have thought it? The most unexpected feature of this election campaign is not the sudden success of Nick Clegg. What has taken us all by surprise is that the campaign has become interesting. Mr Clegg's emergence as the star of the televised debates was not unforeseen. Indeed, it was predicted. What was not predicted was the extraordinary effect that this would have on the whole election.

The debates themselves have been surprisingly watchable. Part of the interest lies in their novelty value, to be sure, and it is not necessarily fogeyish to harbour reservations about the role of debates in a parliamentary rather than a presidential system. Those doubts are different, however, from some of the snootier objections to this democratic innovation. Some observers have suggested that the format has encouraged people who know nothing about politics to treat the election as a kind of game show and to cast their vote on superficial grounds of looks, demeanour and glib sound bites.

That criticism might carry more weight if the alternative to the televised debates were day-long study groups in which circles of concerned citizens studied the manifestos and took part in seminars with party cadres. In practice, the alternative would be further apathy and alienation. Whatever their flaws, the debates have reached a mass audience. Although a lot of the reporting of them has focused on style, process, tactics and opinion polls, the democratic gain has been that perhaps 10 million people have watched at least one 90-minute debate, both of which were serious, policy-heavy engagements.

The effect of the first debate, moreover, was to electrify a campaign that started off in deceptive stasis. Not only was the Clegg phenomenon interesting in itself, forcing people to think again about the settled two-party consensus on issues such as Trident, but it made the Labour and Conservative campaigns interesting, too. As our exclusive interview with the Prime Minister demonstrates today, Gordon Brown is a man energised by the fight that he has on his hands. He was more fluent, more passionate, and altogether more persuasive than we have seen him for a long time. His anger about the Conservative policy to cut inheritance tax further (never mind that he cut it recently) was heartfelt.

David Cameron has also been forced to raise his game, although too often that seems to consist of making a new policy to suit the need for media attention on the day. Yesterday's promise of a law to require a general election within six months of a change of prime minister (as after John Major in 1990 or Gordon Brown in 2007) was a typically foolish and rickety piece of constitutional DIY.

In 1997 the result was pretty interesting, but the campaign was sterile and controlled. The same was true of 1992. The result in 1970 was also unexpected, but the campaign was limp. The campaign of 1983 held a peculiar fascination for Labour's mayhem and Alliance disorganisation; 1979 had some novelty value; but before then campaigns were generally dull affairs.

This campaign has the excitement of a three-horse race. And it sees the intersecting of three remarkable stories. There is Mr Brown, the indestructible man, who has brought himself back from the political dead by willpower and a ruthless exploitation of the economic crisis. There is Mr Cameron, the man who was the future once, who took over the oldest and formerly most successful party in Britain and decontaminated its brand – but not enough. And there is Mr Clegg, at the head of an anti-politics spasm that is now within 11 days of changing the way Britain is governed completely.

All of the above is good news for our One of the Above campaign. We launched the campaign to encourage people to exercise their right to vote, in the week before the campaign began, when the mood towards politicians ranged from apathy to rage. How different things seem now. As we report today, record numbers of people registered to vote by last week's deadline. The way that the campaign has caught fire also means that record numbers tell our pollsters that they are "certain to vote".

Politics is far from perfect, and we have highlighted three issues that have not received the scrutiny they deserve – the deficit, the war in Afghanistan and the environment. But the point is to get involved and change it. And the real surprise of this campaign is that large numbers of people seem motivated to do so. Three cheers for democracy, imperfections and all.