From the reporters’ eyrie up in the rafters of the House of Commons, MPs’ hairstyles are more obvious than their faces. Unless the press pack are trying to identify – to name a couple at random – Michael Fabricant or William Hague, this is more handicap than advantage. But the vantage point can provide the odd interesting tidbit; and the reporters couldn’t help noticing, as Ed Miliband sat awaiting his first Prime Minister’s Questions as Labour leader, that a patch of his hair is turning white in exactly the same way as his brother’s.

Miliband’s party has, of course, been having second thoughts about choosing Junior over his sibling; many would like Ed to develop more of David’s gravitas and authority, and the replication of his brother’s trademark silvery highlight is probably small consolation. But within a few minutes of Labour’s new leader coming to the dispatch box, his party was having a fine old time. For while David Miliband more obviously possesses the ministerial track record and the demeanour to make a convincing statesman, Ed began with a contrived but effective crack at playing the serious and non-partisan national leader.

Sonorously aping Cameron’s reading out of the names of the latest armed forces casualties, he pledged to work cooperatively with the government on Afghanistan. And his deadpan approach began to build up that crucial gravitas – helped, admittedly, by the contrast with the jokey welcome that Cameron extended him: blatantly stealing George Osborne’s snide opening comments to new shadow chancellor Alan Johnson at yesterday’s Treasury questions, the prime minister said he hopes that Ed “does the job for many years to come”. It was probably not, in truth, a joke worth stealing.

Miliband stuck with the bipartisanship on the killing of Afghanistan aid worker Linda Norgrove. The prime minister’s decision to authorise a rescue mission had been the right one, he said – though how the Labour leader knew this, without having seen the evidence presented to Cameron on the kidnappers’ identities and intentions, remained unexplained. He even promised to work cooperatively with the coalition on reforming disability living allowance and sickness benefit. The prime minister responded just as warmly, each man seeking to outdo the other in for-the-sake-of-the-nation generosity as their mature, man-to-man discussion threatened to turn into a cross-bench love-in. Another beautiful relationship began to blossom between a pair of 40-something career politicians – and these two aren’t even in coalition.

Then it all went belly-up. Even before Miliband dropped the faux chumminess, his backbenchers had lost interest in all this political generosity and begun shouting at the prime minister. So they were delighted when their new leader began pressing Cameron on the child benefit cut for higher-rate taxpayers, picking away repeatedly at the discrepancy between the results for single-earner and two-earner families. Would Cameron recognise the cut’s inequity and reconsider, he asked.

The PM wouldn’t address the issue directly, of course. So Miliband kept on putting the question: clasped left hand wobbling up and down as if he was hefting a rock, he found apparently endless ways to ask the same thing. In response, Cameron avoided answering it in just as many ways. It would be more unfair for the poor to subsidise the rich, he said; Labour created this hole, after all; and what would the opposition choose to cut instead? He even managed to crowbar in a reference to Miliband having won his position on the back of union votes.

With a healthy dose of hypocrisy on both sides of the House, each politician could find plenty of ways to fault their opponent. And so the nation was treated to the odd sight of a Labour leader repeatedly pressing for the reversal of a benefit cut that hits wealthier citizens, while a Tory prime minister defended the cut as a way to protect the poor. How times change (though the game of politics remains the same).

Miliband never got an answer, of course: he was good – but so is Cameron. “The right honourable gentleman has suddenly discovered the ‘squeezed middle’,” said the prime minister, with relish. “Who squeezed the middle?”

No resolution, then – but much fun along the way. Afghanistan deaths aside, no subject is too serious to form the subject of a jovial, joyous, childish, pantomime PMQs in the House of Commons. With Miliband seated again, other MPs began asking their questions – and the last came from Tory MP Margot James. Agony aunt Claire Rayner reportedly threatened in her last words to haunt David Cameron if he damaged the NHS, she said; could the prime minister reassure the house that the health service is safe in his hands?

He could – but we couldn’t hear his reassurances. For a theatrical, ghostly wailing was filling the chamber: a Labour MP – Chris Ruane, we hear – was ululating fit to send shivers up spines throughout Westminster. He whooped and wailed and whooo’d; if he’d had chains, he’d have clanked them.

The Labour benches creased up, heads swivelling as they searched out the culprit. And so Ed Miliband’s first PMQs, which began with such an apparently solemn attempt at bipartisan cooperation and adult debate, ended with a return to farcical, ever-entertaining knockabout form. The ghostly wailer probably went on a bit too long, in truth – but that’s often the way with MPs. Like all children who’ve found a way to make their classmates laugh, they don’t quite know when to stop.

And did Miliband look more like a serious leader when the dust had settled? In fairness, he probably did. Given his patient, endless repeating of the question, though; given the shouting and the wailing, and the speaker’s repeated, teacherly interjections to call for quiet, that wasn’t what Ed most resembled. Okay, so he didn’t look like one of the kids – that’s progress. And maybe he’ll look just like a leader one day soon. But for now, he looked like a well-meaning teaching assistant, trying to reason with a confident teenager too used to getting his own way. Ed Miliband was clearly born with intelligence, and he knows what he needs to work at; authority, his party is hoping, will come with time.