Matthew Norman: Truth will out for Coulson and Blair, but don't hold your breath

What a bounteous week this is proving for those who prefer their scandals slow-cooked, and their vengeance on the abusers of power served in lukewarm, congealed morsels rather than piping hot on the one overflowing plate. With the News of the World and its atypically liberal approach to other people's privacy, the tapas keep coming in portions better designed to stimulate the appetite than sate it. The claims of News Corporation that the bugging of phone messages was a charmingly recherché pursuit – Wapping's answer to dressage – disintegrate in super slo-mo.

Private investigator Glenn Mulcaire's confession in court documents that he was told to intercept messages not only by a solo rogue reporter, Clive Goodman, but also by senior news executive Ian Edmondson, has opened a schism at the heart of government. Questioned on the future of the No 10 media chief, the Prime Minister and his deputy contradict each other. Paradoxically, it is Andy Coulson's friend David Cameron who speaks of his guilt, and his enemy Nick Clegg who affects to trust in his innocence.

"The danger," says Mr Cameron, citing Mr Coulson's resignation as editor, "is that he is effectively being punished twice for the same offence." Offence? What offence? Surely this editorial Manuel knew nahhhhhthing? "Sometimes in life it is right to give someone a second chance." Ah, so he did do the crime, but now he's done the time and let's hear no more about it. Meanwhile, Mr Clegg trots out his mantra about Mr Coulson, insisting he had no inkling of any naughtiness, much less commissioned it. So confident is Cleggy about this that he backs an investigation by the Director of Public Prosecutions.

Frankly, this seems needlessly officious. After all, News Corp has both suspended Mr Edmondson and announced an internal investigation of its own. Inevitably, the cynics and sneerers will giggle at this. They will speculate that the firm has decided to cut Mr Edmondson out of its system, like tissue infected with a flesh-eating bug, to prevent the disease spreading. They may wonder whether he, like Mr Goodman, has been offered a large pay-off for his silence.

I cannot sneer. Is Mr Murdoch, who is also assumed to be paying Mr Mulcaire's legal fees (£500,000 and rising), to be traduced because he lovingly cares for any black sheep which stray from his pristine flock? Yet without for a moment doubting this internal investigation and its commitment to unearthing the putrid facts, there is one way it might assume even more gravitas. News Corp should ask Lord Hutton to chair it. He's not so busy at the minute. Most days he can be found sploshing whitewash over the playroom walls – can you see what it is yet? Yes, it's BBC culpability! – at the Widgery Retirement Home for Discredited Judicial Buffoons.

Of course, the tiresome modern penchant for doubting our betters means that even this might not get News Corp off the hook. Hutton never swung it for Mr Coulson's predecessor Alastair Campbell and Mr Tony Blair over Iraq. Nor did Lord Butler's subsequent inquiry, despite it being widely misinterpreted as exoneration by those not fluent in the Whitehall lingua franca of euphemism.

So it is that we now have the Chilcot inquiry, to which Mr T will be recalled on Friday to clear up any confusions arising from his first appearance. If Mr Blair is closeted with his bible on Thursday evening, as Mr Campbell's latest diaries tell us he always was the night before going into battle, the relevant passage won't be the one about heaven loving a sinner that repenteth.

With his gift for legalese, Mr T will elegantly evade all the questions begged by Lord Goldsmith's claim that he ignored his warning that the UN Resolution in no way justified war, and later misled parliament on the point. Even if Peter Goldsmith was a wretch for failing to resign as Attorney General (mind you, they kept the schlemiel so far from the chain of command that he barely qualified as Attorney Lance Corporal), here he carries the unmistakable ring of truth.

This is not something that can be said for all the players in these two aptly concurrent scandals. For 30 years, the Murdoch-Downing Street axis has ruled Britain. Without Thatcher's indulgence, Murdoch could not have grown into the planet's most powerful media player. Without the backing of Murdoch (who believed that an imperial oil grab would keep the oil price low and be good for business) and his feverishly bellicose newspapers, there might have been no British military involvement. Before, during and long after the invasion, it was virtually impossible to identify the border between the government's line to take and the editorial positions of the Sun and The Times. News Corp and No 10 became symbiotic creatures, though which was the host and which the parasite was also hard to tell.

The received wisdom holds, perhaps wrongly, that Murdoch's support remains a sine qua non of winning and retaining power, which explains why David Cameron hired Andy Coulson. He needed a conduit to the grizzly genius across the Atlantic and his lieutenants in Wapping. But in ignoring Norman's First Law of Politico-Media Relations – get into bed with Murdoch, and you will emerge with a rash and a nasty discharge – he made himself a hostage to misfortune.

Now he is paying the price in political capital, by way of the erosion of his credibility. Rumour holds that the PM twice asked Mr Murdoch if there was more to come from the bugging tale to concern him about Mr Coulson, and twice accepted his personal reassurance that there was not. If so, he has the judgment of either a five-year-old or an ostrich, or even (should that bird have the requisite life span; who am I, for God's sake? Bill Oddie?) of a five-year-old ostrich.

Eventually the PM will have to dispense with Mr Coulson, just as eventually it will become universally accepted that Mr Blair wilfully deceived the country about Iraq. But for a good while yet the protagonists in each scandal will continue to tell their half truths, lies of omission and outright whoppers in the familiar counter-productive attempt at damage limitation. This is how scandal unfolds in dozy, apathetic Britain. When we need the high pressure hose to blast away the filth, what we get is the drip-drip-drip water torture from a rusty old tap.