Now, though, I'm convinced that this wasn't part of No.10's script. The clue is in the hurried, and ridiculous, denials that have been issued since. We've had both Brown and Balls claiming that nothing has been done to undermine Darling, and that there's no "poisonous atmosphere" inside No.10. That, lest it need saying, is about as far from truth 'n' reconciliation as it's possible to get. And it's helped turn all this into a split story.
In its way, I think this could be more powerful than the bullying allegations, by themselves. Yes, we knew that Darling and Brown have had their moments; we knew that there's a culture of fear on Downing St; and we knew about McBride, Whelan, and the rest. But this crystallises all those themes in a three-word sizzler – "forces of Hell" – straight from the Chancellor's mouth. And all with the election only weeks away.
At the very least, it should give Cameron some ammunition for PMQs.
P.S. Here's video of the Darling interview last night: