No matter how loyal he would be, David Miliband could not but be seen as a focal point for the (many) Labour MPs who hate all that. Sure, it is a bit odd his saying on Monday "the fightback starts here" and on Wednesday "well, good luck with it guys - I'm offski". But it's better than the alternative. A man who was Foreign Secretary for three years was never going to stay on as his little brother's spokesman for digital inclusion.
And what now? There is a delicious theory going around that Cameron could make him ambassador to Washington. The job is coming up and Miliband would be brilliantly qualified for it. Sure, he'd be called a traitor - but that's pretty easy to get used to when the butler fetches you breakfast in the second-grandest house in DC. It's a little too good to be true, this theory, but there's nothing for him here. Exit, Miliband - stage right. Best for him, best for his party.