With the arrest of the British PM's former press chief, the News of the World saga has achieved a critical mass that will fatally undermine the Cameron premiership. I had been fairly relaxed about the coalition government, seeing it as the only logical outcome of the cards dealt by the electorate last year. But the best Cameron can hope for now is to stagger on as a lame-duck leader, perhaps for years, a la Blair post-Iraq.

At a hastily convened news media conference this morning he obfuscated in respect of the advice he was given from authoritative observers before hiring Coulson and - with reckless hubris - said Coulson was still a friend.

The worm did turn to the extent that Cameron dissed one of the Murdochs - the junior one at least. First he said that when Rebekah Brooks offered her resignation as chief exec of News Inernational, it should have been accepted (ie by Murdoch). When asked if Murdoch should be interviewed by police re his admissions of misleading parliament and authorising pay-offs to buy silence about criminal activity, he said he was not in a position to tell the police what to do, but that Murdoch's comments did raise a number of questions....

Brooks will be lucky to last another week, but in any case will be out by the time Coulson (whome she hung out to dry) has finished helping the plods with their enquiries. But beyond that, don't be surprised if both Murdochs are eased out of their own empire. Rupert's favoured style of journalism is already coming into question in the US, with advertisers backing away from his disgusting so-called news channel, Fox News. No-one with any money will want to be seen giving it to the Murdochs any time soon, and their American shareholders are only inerested in the money.

Cameron will stagger on, but with his confidence shot to pieces, with even the Tory-adulating (London) Daily Telegraph now turning out copy like this:

Cameron in the sewer because of his News International friends