CAMERONOliscarff:Getty

5.00 pm Brown's final statement is all but a resignation speech. And it is entirely a negative speech - sad, hostile, and reliant on the other parties' being "not ready for government." He was feisty earlier but seemed defeated at the end. I sense the bottom falling out of the Labour campaign, and a new energy from the Tories. I misjudged the first debate, so I may be wrong here, and without being in the country it's hard to judge the mood and context.

But I wonder if this isn't a seismic election, in which the two main parties emerge as the Tories and the Liberal Democrats. The only reason Brown gave for voting Labour was fear of the new. Since they're truly sick of the old, his fear-mongering needs to be much more persuasive. 

This was Cameron's night to my mind. And he timed it well.

4.59 pm Clegg: "Don't let anyone tell you it cannot happen. It can."

4.57 pm Cameron says a society should be judged by how it treats the most vulnerable, the poorest. This is a Disraelian one-nation repositioning for the Tories - and, in many ways, Cameron's gentle aristocracy makes him a classic Tory PM - a good butcher with great manners.

4.56 pm It's always good to listen to a political debate where the following words can be said with a straight face: "That's a very silly thing to do."

4.45 pm. Cameron wakes me up. He's looking directly at the viewing audience and being very effective. And the big difference in this debate has been Cameron's willingness to bring up and attack Labour's record. If you are deciding between the devil you now or the one you don't. Cameron keeps reminding people of the devil they know.

4.41 pm. Now we're on welfare abuse. I have to say this gets technical very fast and I find my mind wandering.

4.27 pm Clegg gets rattled on immigration. Cameron says the Lib-Dems are threatening 1.2 million new citizens who could go on welfare. Clegg says that because 80 percent of immigrants are from the EU, Cameron's proposed cap on immigrants is trivial. But if all the EU immigration is legal, then there cannot be any cap on them, can there? without a new relationship with the EU? Maybe I'm missing something.

This was by far the most snippy and biting part of the debate - showing how immigration really does have salience as an issue in Britain as well as the US.

4.18 pm. A minority questioner asks why political leaders don't "get it" on immigration. Brown completely dodges this question. Cameron comes in hard demanding a big new cap on non-EU immigrants. He wants CLEGGGarethFuller:Getty the numbers of annual immigrants to return to the tens of thousands rather than the hundreds of thousands. The question obviously relates to Bigotgate - and Brown decides to answer it by a rehearsed tirade on how many jobs he will bring back. Sad, and devastating for the prime minister. Cameron and Clegg haven't exploited the "bigoted woman" remark. Good for them. Smart too.

Now Cameron skewers the LIb-Dems on amnesty for illegals. Clegg seems very defensive on this - until he gets to the link between illegal immigrants working in the shadows to criminal gangs. Total home-run for Cameron.

4.16 pm. A classic Tory-Labour fight over business and Cameron is endorsing an emphasis on business and away from government.

4.04 pm Clegg is getting more aggressive. And yet aggressively defensive on the euro. He now says he wouldn't take Britain into the euro unless the conditions were right, and he wouldn't without a national referendum. Neutralizes the euro as an issue, but not much more.

Brown goes back to "the same old Conservative Party" line, and is reduced to playing class war. Cameron's responses have been articulate, passionate and yet sane. Over three debates, he has handled himself well, I'd say. He established his low-key calm and affability and allowed Clegg to steal the show, but with each subsequent debate, he has slowly upped the ante and gone on the offensive. Maybe my deep Tory sympathies are blinding me, but Cameron seems like a future prime minister to me tonight, Brown feels like an angry and arrogant old man, and Clegg seems like a worthy, fresh-faced "Here they go again" protest vote against the established political order.

4.01 pm Cameron is kicking Gordon's butt - he's truly on a different level tonight. Now I see more of how he seized the leadership of the Tories five years' ago. I'd seen his sincerity and decency before now - but not the necessary steel for politics. Now I see the glints of steel. I have a feeling he has just won this election.

3.57 pm. The Conservative leader, repeat, the Conservative leader, says the bankers bonuses have been "appalling". He endorses Barack Obama's financial re-regulation bill. He's very strong on the banks, actually - sounding like a Democrat in the US. There's very little in Cameron's manifesto that Barack Obama couldn't endorse in full.

3.50 pm. Brown is making this much more pugilistic and much more of a classic right-left debate, attacking Cameron for defending the rich. Brown keeps shaking his head - Al Gore-like - whenever Cameron speaks. My view is that this has been the Tory's best debate so far by far. Clegg is now getting far more animated, backing Tory themes on lower taxes. I suspect Clegg senses he is no longer the center of attention.

Brown is saying that Cameron wants tax cuts for the very rich while cutting tax credits for children. Brown calls this "immoral". Cameron pushes back saying the tax credits would remain for the poor - not for those above certain incomes. Clegg backs him on that.

3.46 pm. Small point: the first two questioners are minorities - South Asian and West Indian. Both are about fiscal matters. The first wants more candor about deficits; the second wants lower taxes. And what Cameron is doing is trying to pitch a conservatism to this diverse population that appeals to their self-reliance.

3.44 pm This is becoming a real fight between Cameron and Blair, and Cameron is winning. Suddenly, Clegg is receding. Then Brown talks over Clegg for several seconds. Brown is on the offensive. I guess he feels he cannot please anyone so he might as well growl at them.

3.40 pm. Brown's sole point - again - is that there can be no cuts in spending now, which the Tories are proposing. Cameron says he only wants to cut 1 percent of government spending ... and now he's saying he could get some savings by abuse of welfare. A soft blow from the right. Brown actually says that David Cameron reminds him of the Conservative Party of the 1930s! Finally, there does seem some kind of choice here.

3.36 pm. There's something about this huge faux-studio that has rendered the leaders more statesmanlike in demeanor, more like public speakers than TV hosts. To my subjective mind, this has made Clegg seem a little smaller and Cameron more commanding.

The first audience question is a superbly blunt one about dishonesty in spelling out future spending cuts. Cameron is stronger than previously on this, but still dishonest. He pledges to protect spending on police, education and health. But how do you deal with the huge debt with so many items off budget?

3.33 pm. Brown looks dreadful - he looks like he's aged a few years in one day.

Again, his entire opener is about the past, his alleged brilliance in saving the economy from a depression.

3.32 pm. Terrific opener from Cameron: he really does seem to have grown into the role in this campaign, just from the debates. It's striking to hear a conservative make a clarion call for a new "tax on banks." A very timely pledge at the end that he would never support joining the euro, given the Grecian jitters, and Clegg's euro-enthusiasm.

3.30 pm Fantastic venue: the Great Hall at the University of Birmingham. A studio is created inside a vast cavernous Gothic cathedral-style. I guess we don't have many buildings like that in the US.

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