Can it be a coincidence?
Recently, David Cameron admitted that he had smoked marijuana at Eton. A recent poll suggests that, should Brown take the reins of the Labour Party (officially I mean), Cameron is much more likely to be elected.
I put it to you that David Cameron has never touched a joint in his life. The Conservative Party have hired a spin doctor. Smoking at Eton - it's perfect. The upper middle classes will think "That's right, he was at Eton. Must be a good egg". The liberal middle classes will think "Wow, he smoked pot? Can't be such a (insert anti-Conservative slur here) after all". The working classes will think either "Well, it was at school. He seems ok now" and keep voting Labour anyway, or "The Sun says vote Conservative. I'm voting Conservative".
All Labour need to do is find a way of revealing the truth that doesn't look like they're aware of the above, and they'll win some ground back. Surely?