Who "won" the leaders' debate?

The question might be: did anyone win the leaders' debate? Indeed, can anyone win the leaders debate? What is a win and what is a loss in these particular circumstances?

There's the straight post-debate opinion polls, taken in the immediate aftermath of the debate. These show the first impressions of those who watched the action, and are pored over and puffed by the parties' spinners. According to these, last night's winner was not as clear as last week's, when Nick Clegg was declared ahead of the other two: Cameron second and Brown a distant third.

Last night Brown came up strongly on the rails. From 20% in last week's post-debate polls, to 30% this week. Clegg and Cameron, neck and neck and still narrowly ahead.

So, did Clegg win? Or Cameron? Or Brown win? Or was it a three-way draw?

The BBC is saying the "there is no clear winner".

ConservativeHome and the blog of Lynne Featherstone, LibDem candidate, both emphasise the matter of "momentum". They think that the actual result is less important than the strength and direction of the movement of their favoured candidate. Both of these sources claim that the "momentum" is with their man.

Maybe so, and neither Clegg nor Cameron lost ground (broadly), but the momentum argument is about movement, motion: and the motion, according to these polls is with Gordon Brown. From a distant third, on 20% approval in these polls last week, he has leapt to joint second on around 30%. This is a huge jump and, in terms of movement, it is the most real momentum of any of the three men.

If we carry the analogy further and apply it to a three-horse race, the competitor moving fastest as we approach the final furlong is the competitor with the best chance of catching and overtaking the other two. If we really believe in the argument on "momentum", then Gordon Brown has the momentum, he's moving forward faster and further than his two rivals, (who are, relatively, treading water), and Brown now has a chance, at least, to take the race, an outcome that looked most unlikely this time last week.

P.S.

The results of an ICM poll done after the debate.

1.  Who would be best PM?  GB 35%, Cameron 33% and Clegg 26%.
2.  On the same question amongst C1's GB 39 v DC 27% and Clegg 26%, and C2s  GB 39, DC 33 and NC 22.
3.  On who would make the right decisions ins difficult times  GB 43%, DC 34% and NC, 18%.
4.  47% of all voters think DC is more spin than substance, 54% of C1 voters believe that.
5.  On decisiveness GB now leads DC 38 v33 and Clegg at 25.

So, substance can win over style. And GB is substance while DC and NC are PR.