One small but revealing moment in David Cameron's press conference earlier today: when he was asked whether he was warned about specific problems in Andy Coulson's past he said he couldn't "recall" being told. A warning light should go on any time a politician uses that formula. It is neither a denial, nor is it an acknowledgement. It is a holding device that says, in essence, "I don't have a line on this yet, my lawyers have told me to say nothing."

The main impression most people will get from that press conference is that Cameron wanted to deflect this whole story away from questions about his judgement. He failed. In the process he left hostages to fortune. All of those references to his personal friendship with Coulson will be problematic if there is a trial and conviction. Cameron seems to think loyalty to an ex-colleague is an intrinsic virtue here. He said you'd have to be a "pretty unpleasant" person to casually drop an old chum.

But brutally cutting off someone who is damaging you is exactly what a politician in Cameron's position should be doing right now. That's the way it works. People won't respect him for staying loyal, they'll see him as part of a clubbish, mutual back-scratching conspiracy.

The attempt to scatter some of the blame around with references to the Blair era, Bernie Ecclestone's money, dodgy dossiers etc, was also pretty off-key, I thought. It sounded desperate, as if he wanted the whole of politics to take some of the heat when clearly the specific question of whether Coulson was an appropriate person to have running the government's communications operation cannot apply to anyone but the man who gave him the job.

What isn't clear is how much of the public anger over hacking will attach itself to the politicians who failed to get to grips with the issue. The principle villains are still the hackers themselves and the media bosses who tried to cover their tracks. Up to a point, all politicians stand accused of complicity. But the danger for Cameron is that, through the Coulson connection, he is associated in the public eye as part of that reviled media-boss class much more than anyone else in Westminster. He risks becoming the emblem of a corrupt power dynamic. With his press conference today he only made that more likely.