Being Chief Whip is different from being a departmental minister. If, say, Michael Gove had sworn at a police officer – which is highly unlikely, but if he were to have done it – two things would have arisen.
First, people would think it was out of character. Second, he could still have gone into his government department and run education. But when it is Andrew Mitchell, people say that it is wholly in character. Everybody has got an Andrew Mitchell story about him abusing someone.
And because he is Chief Whip, he needs to be able to inspire confidence, and on occasions when somebody has done something that damages the Government, he has got to be able to say: "Look, for the good of the party, you'll have to resign." But if Andrew Mitchell did this to me, I'd retort: "What do you mean? You didn't."
So he's damaged goods. The Chief Whip is effectively castrated. Many MPs have had meetings with their associations and their local activists are saying it's an embarrassment, he's got to go, and the longer this drags on, the worse it's going to be.
If David Cameron won't act, perhaps somebody else will hand Andrew Mitchell the proverbial pearl-handled revolver – but then, he's so stubborn that he's likely to take the revolver and turn it on the person who handed it to him.