Yet it was perfectly obvious that Andy Coulson had to go. Sometimes giving 110% just isn't enough. This blog's argument in October as to why he couldn't survive stands up pretty well (though I was a month out on the timing, in suggesting he was likely to go by Christmas).
The core problem with the "second chance" defence was always that it depended on Coulson having made a clean breast of it when he resigned at the News of the World. It absolutely couldn't survive any revelation which would demonstrate that his evidence to Parliament, as Downing Street director of communications, was less than the whole truth.
So it now seems increasingly likely that Coulson's fate was sealed back in July 2009 when he gave evidence to the House of Commons Select Committee. PR Week suggested Coulson may have given a "career saving performance". Albeit on a longer fuse, with so many seemed reluctant to light for so long, it was very probably a career-ending one.
'I never condoned the use of phone hacking, nor do I have any recollection of incidences where phone hacking took place.'
Coulson sticks to that line to this day. His resignation primarily reflects the strong likelihood that it will come under further pressure in the weeks and months ahead.
So Coulson's evidence tied his personal fate very firmly to the official News International line - captured in its defiant official statement in July 2009 in response to The Guardian's reporting on the unresolved questions in the affair. That statement is under quite a lot of pressure. Even from the police. (Even then, News International's 2007 evidence to the Select Committee had clearly been mistaken in its claim that a full and rigorous inquiry had left no stone unturned).
One former colleague has (albeit anonymously) told Dispatches that Coulson knew a little bit more about it all than that.
"Andy was a very good editor. He was very conscientious and he wouldn't let stories pass unless he was sure they were correct ... so, if the evidence that a reporter had was a recorded phone message, that would be what Andy would know about.
"Sometimes, they would say: 'We've got a recording' and Andy would say: 'OK, bring it into my office and play it to me' or 'Bring me, email me a transcript of it' ...in order to satisfy him that you weren't going to get sued, that it wasn't made up"
Does Coulson's departure matter politically? Anybody who doubts that it does might want to revisit Benedict Brogan's no doubt impeccably sourced report setting out just how keen Downing Street insiders were to promote Coulson's staying power only three days before he resigned.
If it seemed impossible for Coulson to ride out the growing scandal, there was certainly a very active "Save Coulson" operation still firing on all cylinders this week, as Brogan sets out.
In conversations in the past few days it’s been made clear to me that Andy Coulson commands an extraordinary hold on David Cameron and the government machine. It is this bond which explains why the PM shows no sign of being troubled by the difficulties News Corp is having with the Story That Won’t Go Away ...
First, the point about Mr Coulson’s indispensability ... He is considered, frankly, irreplaceable, even if those around him must know that no one is. His departure, they fear, would be a crushing blow to the work of the government at a critical time. This of course, is a way of saying that his departure would be a crushing blow to the credibility of Mr Cameron and George Osborne, who have championed him.
(No doubt, today, Coulson will be just another spinner who the public have barely heard of and whose departure will barely ruffle the government as it gets on with the job). Though the indispensability of Andy Coulson was the view of only one of the two Downing Street tribes. Today's resignation statement will not be mourned excessively by Steve Hilton, whose relationship with Coulson was reported to have reached new lows, by the Independent's Andrew Grice this weekend.
Those of us who have seen this movie before may watch carefully for any revenge strikes. Perhaps this government will have learnt to be more mature than that. But the Tory right will certainly be talking about the need to 'rebalance' the Downing Street operation. (Tim Montgomerie, in his post-resignation tribute to Coulson for ConservativeHome, suggests that his appointment in 2007 came at a low ebb, attributing this to the "lack of balance" in the "uber-modernisers" neglect of Tory themes and constituencies).
The status of Andy Coulson within Downing Street made this a story with a High Politics dimension. But Coulson's role is in some ways a sideshow - and the real issues go much wider than that. As more evidence emerges, the police look at best pretty complacent, and perhaps rather worse. The scandal, and the reluctance to properly investigate it, ultimately raises the question about whether one media organisation with enough clout and contacts can break the law with impunity, and what it might say about the culture of power and law in Britain if turns out that they thought that they could.
It will be interesting to see if Coulson's departure becomes a cue to close down the story, or to open it up.
In politics, it is an important moment for Labour voices to demonstrate that the core motivation was not simply about seeking a political scalp at the apex of Downing Street, a point stressed by Labour Uncut, for whom Tom Watson has led the charge very effectively. And Coulson's departure ought to free up Conservative and (perhaps particularly) Liberal Democrat voices to apply pressure to seeing the underlying issues investigated fairly and on their merits.
It may be a moment too when at least some in our fearless free media - The Guardian very much excepted - might want to ponder as to why it took the New York Times to investigate and reopen a story that many British media outlets shied away from for so long.