The House of Commons was on predictably raucous form for the Prime Minister's statement on last week's European summit. It isn't always a forum in which the best arguments win. Often they are trumped by the most bravura performance, the readiest wit or the exuberance of the backbenches.
On this occasion, the seriousness of the issue just about managed to cut through the roiling theatrics. Cameron pitched his statement soberly, clearly mindful of being seen to revel in the anti-Brussels triumphalism that was bubbling away behind him. He didn't need to worry about sparing Nick Clegg's blushes though. The Deputy Prime Minister wasn't there. Cameron's message was simple enough: the deal on offer wasn't good for Britain, so he didn't sign.
That claim was dismantled by Ed Miliband. Nothing had been vetoed that cannot proceed anyway, no safeguards were secured and all that was achieved was Britain's marginalisation. It wasn't a barnstorming performance, but it had the solid virtue of describing the truth.
The message was reinforced by needle-sharp questions from two former foreign secretaries, David Miliband and Jack Straw, probing the Prime Minister on the detail of what exactly it is that was under threat before last Thursday, and how exactly the threat has now been averted. Cameron couldn't answer.
Outside parliament, though, It doesn't really matter much. The Prime Minister's strongest line was also his most predictable one: would Miliband have signed or not? "You can't lead if you can't decide". It was a neat barb, crafted to reinforce No. 10's central strategic line of attack against the Labour leader -- that he is not a credible alternative PM.
Ultimately, Cameron is confident because his stance is popular. He is casting himself as the PM who finally said "no" to Brussels and, according to opinion polls, it is working.
That domestic political advantage (which has the added benefit of averting a rebellion on his backbenches and diminishing the threat of a Ukip upset in next week's Feltham by-election) has led a number of Labour MPs to query whether Cameron might have planned the whole thing. The theory doing the rounds is that he deliberately tabled impossible demands in Brussels to engineer a veto.
Just before the statement, I spoke to one shadow minister who put the question pretty bluntly. "Is it conspiracy or is it cock up?"
If it is the former, the Lib Dems will have been most royally stitched-up. Perhaps suspicion along those lines is what kept Clegg out of the chamber.