I was planning to write a lengthy post on how I think I was unfair to David Cameron in my CPS paper on the Conservative Party.

In the paper, I wrote this:

We were...informed in a supposedly seminal speech in June by David Cameron that the distinctive Conservative agenda comprised:

A dynamic economy. A decent society. A strong self-confident nation. These goals are forward-looking, inclusive, and generous.

It is difficult to imagine a sentient being who might disagree with Mr Cameron’s offering. The Conservative Party will have to do more than ape Mr Blair by removing verbs from sentences if it is to return to electability. Nor was Tony Blair elected Labour leader simply because he was young and had a pleasant demeanour...[I]t is notable that David Cameron’s sole public contribution is to have been policy coordinator for a manifesto which secured a third successive electoral drubbing.

I stand by all that. But I think, with hindsight, that the tone was too harsh and that I did not give proper attention to some of the speeches he has been making of late - and I mean speeches well before his party conference triumph.

More to the point perhaps, David Davis' performance was so dire that as far as I can see he has - or rather should have - destroyed any chance of winning the vote-off between the final two. If he couldnt even keep his own party awake, what on earth will the rest of us think of him?

It's become the fashion this past week to say that he wasn't as bad on TV as in the hall, and that it's only the Westminster elites who are saying he was so bad. Nonsense. I watched the speech on TV live, and as he was speaking I said to a friend on the phone that I was watching a political career destroy itself. The speech was a train wreck, pure and simple.

Since Clarke would be a disaster, that leaves only Fox and Cameron as serious possibilities. And, having listened to Cameron in Blackpool and read his speeches it is clear to me that he is the only sensible choice.

Or so I thought. For the life of me, I cannot understand his behaviour in response to the drugs question. I have no idea whether he took illegal substances or not, but let's assume the worst. His response ought to have been straightforward. Instead of playing his current coy games, talking about 'mistakes' he might have made, and then refusing to answer the question, he should simply have said 'yes, I did, I was young and foolish. I have never taken anything illegal since'. End of story. It didn't stop George Bush winning two elections, and it wouldn't stop Cameron.

What might stop him is the idea which cannot but take hold if he continues to refuse to answer the qurestion - that he has something to hide.

It matters because it is not, as Cameron, would have it, an illegitimate quesion. To say that the question is entitely irrelevant is simply wrong. Some of Cameron's supporters have said that it is no more relevant than asking if he once drove at 35 mph in a 30 mph zone when he was 19.

Come off it. To equate a minor infraction of the law, such as speeding, with abuse of illegal drugs is not merely fatuous but downright worrying, since it implies that he has no idea of the consequences of drug abuse.

Taking illegal drugs remains, whatever some people might want, a serious offence. Asking if a man who wants to be PM committed a serious crime is far from irrelevant. It is entirely proper. What is improper - and politically stupid - is Mr Cameron's attempt to brush it off. At the very least, it looks like yet another example of the moneyed middle classes behaving as if there is one law from them and another for the rest of society, such as those whose lives are ruined by drugs. There is a direct link between the decision by the well-off dinner party circuit to take illegal drugs and the destuction of lives elswhere.

But if, assuming he has taken drugs, he had come clean straight away, it is almost certain that the issue would now be dead and buried. As it is, Mr Cameron's refusal to answer the question ensures that it will continue to dog him - and, perhaps, fatally undermine him.

PS I should add that I backed Clarke on the day after the election on Betfair at 78.8/1. I still don't think he'll win, but at that price I had to have a tenner on...