Art yesterday, Politics today.

What a great advert Boris Johnson is for David Cameron's earnest but never less than bumptious, young turks. Cohort number four has had to trudge out of Boris's City Hall wreathed in disgrace: it's like Spinal Tap in there. Ray Lewis goes for a walk, Tim Parker out to grass, James McGrath forced in to exile, and today, David Ross.

Boy, can Boris choose people. Four of his inner circle gone in seven months. I'm so impressed. Bet David is too.