This was exactly the kind of performance which will keep Ed Miliband in the job just long enough to lose the next general election.
By Alex Stevenson Follow @alex__stevenson
Despite all the drawbacks associated with being a middle class policy wonk from north London, the Labour leader - fresh from yesterday's mediocre relaunch - returned to the Commons chamber fray with aplomb this week.
He did what he does best: picking up on an important but under-reported issue, far from the top of the prime minister's pile of briefing papers, and teasing Cameron with it.
Today that issue was train fares. Like many of Britain's rail services he was running a little late, as we've known these would be rising by up to 11% for some months. But this was the first PMQs since they actually went up, so that didn't matter. More importantly, it gave him a chance to inform the prime minister that he was thoroughly wrong.
"He is wrong," Miliband pointed out. "He is just wrong," he added, underlining the point. To ensure that the fact Cameron was wrong was completely in the mind of the listener, he added, for good measure: "He is simply wrong on the facts." Politicians understand the use of repetition to get a point home, but really - we get the idea.
The substance of the dispute was thoroughly tedious, resting on whether you accept that the Labour government's rule change to train fare flexibility in an election year was a permanent shift or not. Bo-ring! As Cameron complained, Miliband is happy to welcome good news of investment in the railways, but never has to make the "difficult decisions" behind them. But that didn't matter. What mattered was it gave Miliband the opportunity to inform the Commons once more: "The prime minister is wrong."
After a brief break the leader of the opposition returned, raising the Scottish independence referendum. He, Cameron and Nick Clegg are thoroughly united on this. "We are going to be in 100% agreement," Cameron declared.
As soon as the PM and his deputy began nodding their heads to Miliband's platitudes you could tell the remaining exchanges would be tedious in the extreme. So attention shifted to the SNP benches. Their presence in the Westminster parliament may be small, but it is not quiet. Western Isles MP Angus MacNeil heckled throughout, his gleeful contempt standing alone in a chamber otherwise silent. He appeared to think it would be a good idea for Cameron and Miliband to demonstrate their agreement symbolically through a physical gesture."Hauld his hund!" he cried out repeatedly, clasping his mitts together.
Angus Robertson, the SNP's leader in Westminster, stood up later in the session to offer some advice of his own. After being roundly jeered by backbenchers on both sides of the House, he observed that the Tories had less MPs in Scotland than there are giant pandas in Edinburgh Zoo. He wanted to know why Cameron was so keen on emulating Thatcher in his desire to dictate to Scotland. The hostility was, in short, intense. We can expect a fight on our hands in the coming months.
The constitutional crisis triggered by this week's Scottish developments seems to have dimmed the intensity of last year's big topics - Europe, the economy, benefits. Cameron dealt with these issues without batting an eyelid. He even found time to praise the achievements of a certain octogenarian sub-postmaster, Tony Whattling, who has been in charge of an independent post office in Westhall for the last 60 years. "It's people like that who keep our country going," Cameron observed. Political careers rarely have that kind of longevity. All present - especially Miliband - looked impressed.