"Amazing," senior reporters whispered to themselves. "Extraordinarily hilarious", Chris Bryant said afterwards. What started as a setpiece example of MPs' hostility had quickly descended, unexpectedly and absurdly, into farce.

John Yates could have done with a bit of humour as he struggled, desperately, through a gruelling grilling from vicious MPs.

Their curled lips and sneering expressions would have made Churchill quail. Not since the bankers were hauled up before the Treasury committee have I been in a committee room filled, almost tangibly, with open enmity.

There were eyes everywhere. The journalists, scribbling away in their notebooks. The members of the committee, who - when they were not engaged in direct questioning - muttered darkly to each other, never bothering to veil their utter disapproval at Yates' conduct. To the side, another row of MPs, interested spectators with a special line in contempt. David Davis, hands behind his head, and Tom Watson, arms sturdily folded across his frame, were statuesque in their condemnation. All those eyes, boring into Yates' conscience. This is what is known in the profession as a 'tough gig'.

Then there was Chris Bryant. He began with was mere head-shaking. Then the hand crossed his furrowed brow in disbelief. He shrugged theatrically in disbelief at what he was hearing. Towards the latter stages, Bryant was the first to crack by laughing out loud. Several times he was mentioned, in references veiled or otherwise. He was like the ghost at the feast, flitting in and out of the committee room. Only everyone knew he was there.

The jokes were still to come as Yates struggled on. His problem, exploited to the full by Keith Vaz and co, was that he had admitted "regret" - but only with "the perfect glare" of hindsight. Given his refusal to resign - and it felt like he made virtually every concession bar this final, decisive one - he might have been better off being a bit more bullish.

Nothing was to match the fighting spirit of Andy Hayman, who appeared later on in the session. The man in the hot seat for the original 2006 phone-hacking probe, which resulted in two convictions but let the vast bulk of alleged wrongdoing get away, was - according to Tory MP Nicola Blackwood - "more like a tabloid journalist than a police officer".

He was a breath of fresh air, that's for sure. How extraordinary that someone in such a key position in the original probe, who must have soberly observed the unfolding of this monstrous scandal, could not muster up the tact to handle these questions in a less hapless fashion. "Don't beat me up for being upfront with it, or honest," he protested at one stage. The truth is he was beating himself up.

The room had emptied somewhat after Yates' grilling, but it was still standing room only as incredulous MPs pressed on. This "dodgy geezer", as Conservative MP Lorraine Fullbrook called him, was perhaps a bit too honest.

"You have made a judgement call to accept hospitality from people you are investigating over criminal offences?" one MP asked. Hayman replied, with the high-pitched off-handedness of one conceding a minor point: "Yeah!"

He then claimed it would have been more suspicious to have refused the dinner. Cue laughter. "I don't know why you're laughing," Hayman protested. His feelings had clearly been hurt. "We're laughing because we are astonished, Mr Hayman," Vaz observed placidly.

This was one of several eminently quotable exchanges, any one of which are - on a normal day - grasped by sketchwriters as manna from heaven. It was preposterous, unthinkable, unfeasible that anyone who had once been so senior could be so clueless.

What a transformation. The full weight of moral indignation which weighed upon John Yates had been replaced with an unreality which somehow defied censure, through the usual channels at least.

"I feel a little bit like I've fallen down the rabbit hole," Blackwood observed. She wasn't the only one.

Follow Alex Stevenson on Twitter: www.twitter.com/alex__stevenson