Steve Richards: Biggest game changer is that voters were engaged

History is made and it was oddly familiar. I feared the first leaders' televised debate would be stifled and stilted. Instead there were times when the exchanges had a knockabout quality to them. Three very nervous leaders acted more as they do in Prime Minister's Question Time, the only forum they are used to clashing with each other. Until last night it was all they had known.

In the early tentative clashes Gordon Brown taunted David Cameron over Michael Ashcroft. Cameron exclaimed once or twice that Brown had 13 years to address the questions raised. Nick Clegg attacked both the old parties and looked towards a new politics. "The more I hear of you two, the more I think you are the same," he declared. The manner was familiar too. Brown was solid, lacked tonal variety, but had one or two of the best, carefully prepared lines. Cameron and Clegg were deftly conversational. The weekly battle in the Commons had moved to the television studio.

Where last night's version topped the regular gladiatorial jousts was in the occasional interchanges between the three of them. On several issues Brown made overtures towards Clegg, most specifically on constitutional reform. "I think Nick agrees with me on this, but David opposes both of us." Every move in this game was calculated in advance and evidently Brown had decided to imply alliance with Clegg, leaving Cameron isolated. Clegg was having nothing of it. At one rare moment of apparent spontaneity Clegg was caught smiling and despairing at the same time as Brown claimed the two of them were in agreement about the need to modernise the Commons. It was his turn to point out that Brown had been in power for a long time and opposed his various proposals to reform the voting system and the House of Lords.

Gently Cameron challenged Clegg over his piety when his party had been funded by a "criminal on the run". More robustly he tackled Brown. There was little common ground, but the differences between all three of them in the early stages came across as being more managerial than ideological, a values-free debate about how a trio would set about running a country, as if they were being interviewed for an administrative post. All had proposals to manage the "problem" of immigration. All were concerned about crime. Cameron referred to his mother's role as a magistrate. Brown recalled his father setting up a community centre, attempts to humanise on a night when voters were paying rare attention. A visitor from Mars would not have had a clear idea early on where each of them stood on the political spectrum.

The arguments came to life over the economy and public services, issues that define the leaders' politics more clearly. Brown had set the pace by outlining the argument at the very beginning, highlighting the risks of Cameron's plan to start cutting public expenditure this summer. Cameron had no convincing answers as to how such a move would improve the economy, let alone public services. Here there was more of a coming together of Brown and Clegg. The Liberal Democrat leader declared with a distancing formality: "David Cameron, you can't offer tax cuts for millionaires and find money for public services." Brown added in a way that was becoming a pattern: "Where Nick and I agree, there is no argument for David's inheritance tax cuts." Cameron seemed least comfortable on the economy, but otherwise he was composed.

The event was on trial as much as the party leaders. I would have preferred fewer topics and more interaction between the three very different personalities, but on the whole the 90 minutes were looser and more revealing than I thought they would be. It felt significant although that might be because the event in Manchester extended beyond the TV studio to a media centre, which became an extraordinary political village for journalists and politicians.

The winner was Clegg, partly for being there. In front of an audience his predecessors would have died for he was calm and authoritative while managing to pull off the awkward balance of appearing distant from the leaders of the bigger two parties without seeming eccentric and on the margins. Crucially he seemed relevant. By the end he was almost shameless in his proclamations of dismissing the others while promising vaguely "real change". This was when each of them offered compressed summaries of their pitch in this election. For Brown it was about securing the recovery. For Cameron it was optimism about change.

Voters were watching peak time politics, a novelty in itself. But they witnessed no great game changer from the leaders. Instead their fleeting engagement with politics will go down in history as something of a game changer in itself.