Steve Richards: Liberal Democrat leader prevailed over the three legs

More than the other two debates a verdict depended on the voters' attitude towards the parties. Before a word was uttered last night a pattern of sorts had formed in the polls. With a week to go the Conservatives are ahead with support in the mid 30s and the other two parties are battling it out with Labour in third place. Not surprisingly the instant polls after the debate reflected what is a fairly settled position. So close to polling day and with the economy the central issue subjectivity plays an increasingly bigger role.

Those that have long believed that David Cameron and George Osborne made a fundamental error when they called for spending cuts at the height of the recession would not have changed their minds by last night's exchanges. Voters who support the Conservatives' approach to the economy will have given Cameron the thumbs up as he sought to defend his economic policies against a passionate onslaught from Gordon Brown.

After his clash with a Rochdale voter the pressure on Brown was greater than ever. Not for the first time when superhuman resilience was needed he acquired a fresh sense of urgency, having been caught on camera slumped in a radio studio the day before apparently drained of energy. Brown's opening statement was well judged, a sensibly restrained passing reference to the calamitous drama with his voter, and then a powerful argument against cuts in public spending this year.

At least I judged it to be a powerful argument as I am opposed to immediate spending cuts. For those voters who believe the Conservatives' misread this recession Brown exposed their inconsistencies and misjudgements with a sense of passion he has lacked in the other two debates when he tried too hard to appear 'prime ministerial', was buttoned up and lacked agility. He highlighted effectively the immediate dangers of the Conservatives' planned emergency budget and the iniquities of the commitment to abolish inheritance tax, an increasingly aberrant proposal. But for those voters who are convinced that the Conservatives have scope to cut this summer Cameron would have reassured them that their convictions are wisely held. There are more of them than there are those who support Brown. Not surprisingly they called it for Cameron.

Stylistically the debate was very different from the two that preceded it, perhaps reflecting its proximity to polling day. There was much less mutual politeness. Cameron described Brown as offering "desperate stuff from someone in a desperate state". Later he suggested that Brown should be ashamed and towards the end that he was a tired prime minister who had nothing else to say. Brown contrived every answer to make sure in relation to the economy he tore apart Cameron's approach. Even more than in the first debate, Nick Clegg sought to play the plague on both your houses role. Last night he sought to play it too hard. He accused the other two of "political point scoring" when they were engaged in a perfectly valid debate. On the economy he suggested a coming together of the "Chancellors and vice-chancellors". I do not know quite what he had in mind but it did not sound very credible. Are differences between parties not permissible in the so-called 'new politics'?

Later the dynamics became more familiar. Brown lapsed into reciting lists of objectives and policies. Voters who might have been paying more attention to him at the beginning would have switched off. Clegg was adept at dealing with the attacks on him: "Let's save time by assuming David Cameron misrepresents our policy". Cameron was more relaxed once the section on the economy had passed and articulated his policies effectively as he has done in all three debates. Part of the weird mythology about these debates is that Cameron has been a poor performer.

But Brown returned to his overriding theme. The other two were both a risk in relation to the economy. When he did so he came back to life. Given that he was in political hell 24 hours earlier, and that his economic policies are closer to what are required – much closer to the US and equivalent countries in Europe too – he deserved to score better last night. Clegg was less effective, although this might be because we are used to him now in this elevated context.

But voters are starting to make up their minds. Clegg was the winner when all three are considered. Cameron has cause for optimism and these are very dangerous days for Brown and his party.