Only a month ago Ken said he wanted to drop negative campaigning:

I suggest to Boris Johnson therefore that he and I work together to raise the tone and spirit of this election. Let us talk about what really matters to each and every Londoner, and end the X-Factor slug-fest.

We want to concentrate vigorously on those issues that can make Londoners better off over the next month of this campaign.

As you can see Ken’s campaign today paints Boris as an alien blue slug. Not exactly a positive focus on the issues…