While he's not busy de-anti-racism-ing the city's festivals, London mayor and professional posho Boris Johnson is speaking out about the positive effect of pop stars on knife crime.

"Tackling the horrific spate of knife crime in London is my top priority," he says.

And what is making that easier?

“I am greatly encouraged to hear that Lily Allen, who has a tremendous young fan base, is speaking out against violence and wants to do something positive."

We're not sure how much Lily Allen approves of Boris Johnson, given that it would be easy to swap Bush-baiting for Boris-knocking in new demo Guess Who Batman:

So you say it's not okay to be gay / Well, I think you're just evil / You're just some racist / Who can't tie my laces / Your point of view is medieval

Yeah. Still, knives are bad, mmmkay?

Gigwise: Boris Johnson praises Lily Allen for condemning teenage knife crime