As I do a fair bit of media-whacking, let me start my post-debate analysis with a few words of praise for Alastair Stewart. The ITV chair of the first leaders’ debate resisted the temptation to make himself a big part of the procedings and he moved events along at a good pace.

As a TV programme I thought it worked. I really hope that millions of people who don’t normally engage too closely in the political debate watched, and that it made them really think about the issues in this election.

I thought Nick Clegg did well. Go back and read every blog I have written on these debates – oh ok, just take my word for it – and you’ll find I have said from the start Clegg would do well. It was a fantastic opportunity for him, and he took it.

But of the three men up there, only two can be Prime Minister after May 6. And of those two, GB beat DC hands down. Gordon won the debate on substance. Cameron was the runaway winner on shallowness. He seemed to get shallower the longer it went on. Beneath the veneer there was more veneer. Penetrate the generalities and there were more generalities.

GB was strong, authoritative, energetic, policy and substance focused, but also with occasional nice light touches. He was the only one who led the audience to break the rule on clapping.

Cameron had a nicely written opening statement which he delivered perfectly well. But once they got into exchanges on policy, he seemed unsure of himself.

He was good at doing his usual – trotting out pre-scripted lines and slogans, but he was poor in the exchanges between the leaders. I have been saying for yonks that he is great at presentation but poor on policy and strategy, the stuff that really matters. This time he wasn’t even that good at the presentation.

I have been inside Cameron’s head, or trying to get inside it, for some time now as part of GB’s preparations team for the debates. And I really did expect the Tory leader to do better than this. I have been giving Gordon a real pounding on some of his past statements and policy outcomes, but DC seemed not really to be up for it. It was also surprising that within a day of launching the Big Society as his big idea, he seemed to have dropped it already. He must have seen the polling I mentioned in my pre debate blog.

I was surprised too that he didn’t push back harder – or indeed at all – on the charges from GB about the impact on public services of his economic plans. The Tory risk is going to become a bigger issue from now on in.

As for his inclusion of China in his answer about why we need to keep nukes, I’m sure that went down well in Beijing. Not.

The spin room afterwards reflected the general feeling I think. Vince Cable smiling. Alan Johnson spelling out the consequences of Cameron’s failure to match Labour on police spending. Peter Mandelson enjoying winding up George Osborne who, a bit like Cameron earlier, looked like he would rather be anywhere else. Every campaign has an ‘oh shit’ moment. George looked like he had just had his.

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