Prime Minister’s Questions sketch by London Editor Graeme Demianyk.
There are weeks when Prime Minister's Questions resemble little more than two grown men (and very occasionally, a woman) shouting at each other. An unedifying spectacle to many, a show that confirms why people are put off politics, the riot of bellowing, furious finger-pointing and end-of-pier humour is the highlight of the political week for others. You often emerge from the chamber, in the mother of Parliaments, and wonder: what was that all about? Still, you reflect, same time next week, eh?
This week was different. This week, Prime Minister's Questions had a sense of purpose, a raison d'etre, beyond the leaders of Britain's two biggest political parties knocking seven bells out of each other. The reason? Europe.
It was Europe that prompted a chorus of cheers from Conservative backbenchers as David Cameron made his way to the dispatch box, his sculpted quiff bouncing more than usual. This was the kind of acclaim usually reserved for a century-making England batsman after putting Australia to the sword, and you half-expected the Prime Minister to raise a bat and salute his team-mates and supporters.
To be clear: this doesn't happen every week. While polling shows Mr Cameron to be more popular than his party with the general public, there are within his own ranks those that have long had reservations about their leader. What does he believe in? Is he even a Conservative? Is he really the eurosceptic he proclaims to be?
Mr Cameron received the hosannas because he delivered what many from his parish long craved: a pledge of a referendum on leaving the European Union. That it will be in 2017 was almost by-the-by. There are some Tories who couldn't have been happier if they were five years old and it was Christmas morning and David Cameron bought them the shiniest bike in the shop.
Since the big reveal came in a speech delivered at 8am yesterday morning, Prime Minister's Questions at 12pm was lent a frisson of excitement. To many, the UK Independence Party beast, which is campaigning to get Britain out of Europe, had been slain. Now the Conservative leader was eyeing a second bird with the same stone: the Labour party.
With the Tories taking the initiative and running with it, how would Labour respond? After all, and if you believe the Conservative Party argument, the "people" want a say. Even europhiles favour a referendum to put the issue to bed once and for all, they say. Would the Labour Party deny them that right?
Labour has arguably painted itself into a corner. Jon Cruddas MP, the party's big thinker, recommended months ago that Labour strike first and make the pledge while Mr Cameron was being buffeted by his backbenchers.
Labour leader Ed Miliband, greeted by ironic Conservative cheers, had to box clever. And it started well.
"Can the Prime Minister guarantee that if he gets his in-out referendum he will campaign to stay in?" began the leader of the Opposition, in civil tones.
The Prime Minister returned, gently: "Yes, I want Britain to be part of a reformed and successful European Union."
And there's the rub. The Prime Minister's referendum pledge follows re-negotiations with various European institutions in the hope of clawing back powers. The threat of a referendum, it is hoped, will bring pressure to bear.
But many on the Tory right are avowed EU "outers". And while Pensions Secretary Ian Duncan Smith and Education Secretary Michael Gove are sympathetic, former Chancellor Ken Clarke and ex-Deputy Prime Minister Michael Heseltine are fiercely opposed to withdrawal. This is the schism Labour will seek to exploit. Divide and rule.
Mr Miliband, on the attack, went on: "The only thing that has changed is that a few months ago, when he said he was against an in-out referendum, is not the situation in Europe, but the situation in the Tory party. Why does he not admit it? He has not been driven to it by the national interest, but dragged to it by his party."
Then, danger. The Prime Minister, going on the fishing expedition he'd planned the whole time, asked whether his adversary wanted a referendum, adding: "I do. Does he?"
Mr Miliband: "My position is no, we do not want an in-out referendum."
So there it is. The first battle-line of the 2015 General Election. A referendum on Europe, vote Conservative. If not, vote Labour. The choice couldn't be starker (though Labour officials later claimed this was over-stated). Now, over to us. Possibly.