Ultimately, the success or otherwise of the The Leaders' Debate will be measured not by the after show polling figures or the numbers of points parties gain or lose on election day, but how it effects turn out. According to the Graun, 9.4 million tuned in, and it's probably fair to say a good proportion of them are not only undecided over who to vote for, but also whether they will vote at all. I'm pretty sure some enterprising political science-types are already trying to design research that will offer an approximate answer to that question.
It is fair to say Nick Clegg won the evening, but when all is said and done, regardless of the punditry puzzling over Brown's choice of shirt, whether Clegg was right to address the camera over the audience, and Cameron's hand gestures, it is the political fare that matters. Brown's strong suit was the economy and he played this hand well. Clegg's positioning himself as a slightly more radical alternative to the other two is what enabled him to win the night. And Cameron, well, it will come as no surprise to say I thought most of his policies were piffle. But what really came through is how fundamentally similar all three leaders' politics were. We had the disgusting sight of them competing to be the toughest on immigrants (which, sadly, probably went down well with a lot of viewers). On defence spending it was wrangling over the number of helicopters that should be in the field - Clegg showed the depth of the LibDems anti-war credentials by not once questioning whether the war in Afghanistan is right or just. But it was also Clegg who raised the case against Trident, to which the others could barely give a coherent rebuttal.
And so it was with policing, education, health, MPs' expenses - they were all pretty much singing from the same hymn sheet. Small wonder the pundits are obsessed with the form in which the arguments were delivered than their substance.