Ed Miliband put in one of his stronger performances this week

PMQs sketch: Into the abyss

PMQs sketch: Into the abyss

David Cameron's defiant, sneering response to the Liam Fox affair is about as reassuring as some cheery words of optimism from the captain of the Titanic.

By Alex Stevenson

Prime minister's questions is best thought of as some sort of political megaphone, amplifying any bad behaviour in the last week and making the Westminster world look even worse.

The last week has seen ex-defence secretary Liam Fox resign for the shady activities of his close friend Adam Werritty. You'd expect the prime minister to accept his weak position and show some dignity in response, wouldn't you?

That just won't cut it in the PMQs bearpit. So instead Cameron came out fighting, mudslinging gamely.

The effect of this week's exchanges was that it resembled some sort of hideous parliamentary nosedive, in which the pair's jibes brought the reputation of politics plummeting downwards.

Miliband raised the "money trail", flagged up suspicious figures with "close links to the Cabinet" and warned of a PM whose defence secretary had resigned and spin doctor had been arrested – as he and Cameron clung on to each other's necks, rushing downwards.

Cameron praised Fox for resigning before smearing Labour's record of "cabs for hire, passports for favours, mortgages for mates, dodgy dossiers", as he and Miliband rushed in their mutual death grasp towards the hard, unyielding verdict of public opinion.

The heckling from both Labour and Conservative MPs was so intense that Speaker John Bercow had to plead with the backbenches to stop their "organised barracking". You could almost see the party leaders' hair waving in the wind as they fought on in the tumult around them.

All very typical for a prime minister's questions, of course. And such is the nature of British politics that there won't be a mutual 'splat!' moment of oblivion. Westminster doesn't work like that. Both dust themselves down, and get ready for another week.

So we're left trying to work out who was the winner or the loser. We try to work out whose reputation has been less bloodied than the other.

Cameron has become very good at duffing up Miliband. But his primary defence on the Werritty case was that the Labour leader's criticisms were a bit "late". "I've got a bit of advice for him," he said, trying to look as nonchalant as possible. "If you're going to jump on a bandwagon, make sure it's still moving!" The Tory benches roared with laughter, but Miliband looked very chirpy after his first three questions on the Fox affair. One-nil to the leader of the opposition, that's for sure.

After a brief pause Miliband resumed with three more questions on the economy. He had his tail up after the Fox bashing, and delivered a rare roasting of the prime minister. Cameron was skewered most effectively through a favourite opposition tactic, of asking the PM how a poorly performing something-or-other is doing. Of course Cameron didn't have a clue what the answer was. This time it was the Regional Growth Fund, which, as Miliband announced gleefully, had handed cash payments to just two firms in the last 16 months. "First of all," Cameron began, dodging desperately, before Labour MPs pounced. "I don't think he knows the answer," a rather sly Miliband replied.

There is no question that Miliband emerged the winner of this session. But he must be careful that he does not talk the economy down. "We've had 18 months of his economics experiment, and what's he got to show for it? More and more businesses going bust!" he said, sounding gleeful. "More and more people losing their jobs!" he said, sounding delighted. "Inflation through the roof!" he said, sounding over the moon. A trifle more tact might be a good idea.

This is the way of politics, or at least the way of prime minister's questions. The purpose is to bash the enemy, and nothing else. You might think the good of the country has next to nothing to do with it.