McBride's quick depature had three objectives.
1. Close down the story. This seems to have worked: today's news doesn't have many more developments. If tomorrow's papers have nothing new, then Damiangate may not last until Wednesday. This would be, in the circumstances, the best possible outcome for Brown as there is a far more dangerous aspect to this story as yet unwritten: how the tactics exposed by McBride's emails (ie, character assassination) were the weapon used by Team Brown to take out his potential rivals for No.10. This time, the Tories were the target - but similar tactics were used to destabilise a long line of former (and some serving) Cabinet members.
2. Position McBride for quick return. Crucially, McBride is only down for a minor offence: sending "juvenile" emails. Which (as Draper keeps telling us) he did in an hour. And McBride himself has said he's gone simply to honour an old spin doctor code: when you become the story, you have to go. Sounds almost noble of him. Mark my words: McBride is the best spinner Brown has. He can be courteous, informative and immensely useful to the journalists he regards as strategically important. His skill in bridge-building with potentially hostile papers is too valuable to lose during an election campaign. He'll be back.
3. Protect others potentially involved. Liam Byrne has been carefully defining the question for us today: who knew about the emails? The real question is who knew about the concept of a Red Rag attack site. Who approved it? Is No10 really so dysfunctional that the PM's chief of strategy and communications can be allowed to freelance in this manner? More people will have known about all this. It's called Black Ops, it has to be deniable - but plenty people will have known something was up. McBride's quick departure is designed to stop people asking who these people were.
We'll have a clearer idea tomorrow if this Bob Quick approach to crisis management has been successful. But under the circumstances, it's looking good so far.
We have to keep turning this over, precisely because the Gorgon wants it to go away. And if it does go away, cui bono?
Don't let this one die.
Update: Alastair Campbell, of all people, hints that there is more to come.