I agree - leave Boris alone, people voted for him because he doesn't wear a helmet and that's the way we like him.
By the way I was in a cab on the way back from work late the other night. The driver said in disgust - "look at that cyclist, no helmet, tut, tut, tut" (he hadn't muttered a word up to that point). I just told him that it wasn't a legal requirement (he seemed genuinely amazed) and wasn't it interesting that cyclists that wear helmets are likely to be overtaken more closely than those that don't (he wasn't so interested in that argument). But interesting that he thought that the guy was riding illegally. I wonder how many other ways people think we are breaking the law when we aren't.