Lord Ashcroft's research puts the Boris "appeal" in it's true light.

The research into the appeal of Boris Johnson by Lord Ashcroft is characteristically thorough. It says to me that the old adage that you can fool some of the people all of the time and all of the people some of the time but not all of the people all of the time seems to apply. Boris has his loyal supporters who think he is the answer to the question - the question being "Who can get the Conservative Party power". He has his detractors, me included, who would not vote for him even if he was standing to be leader of a Parish Council. But most voters surely see Boris as likeable but not credible as a figure standing on the same stage as Merkel or Obama. The research confirms this.

Lord Ashcroft seems genuinely to think that Mayor of London is a proper job and that Boris has been good in it. In fact he has been good at what he's good at - he was the ideal Mayor for the razzmatazz of  London 2012 and he did well. But the Olympics aside the truth is that the Mayoralty isn't much of a job at all - and Boris seems pretty bored by it. The hands of the Mayor are tied by the very narrow remit the job has. So Boris uses it as a personal platform and most of his speeches and pretty much all of his writing in his Telegraph column and elsewhere are not about London at all.

Boris's enthusiasms are the ones that grab the headlines. The Airport in the Thames Estuary idea is much more "in your face" than the far more logical, but boring, expansion of Stansted/Gatwick/Heathrow . The latter doesn't grab headlines, the former does. That's why Boris is for it. He is a skilled self-publicist and a bit of a card. That is why people aren't over-bothered, at the moment, by his adultery and his lax morality. But if he was the Conservative leader they would be. It would be unprecedented in modern times to have a philanderer as Prime Minister - we might regret this and argue that the public and the private lives of our leaders are separate things. But that is not how it is. Lloyd George ( and others) got away with being a goat because the then media was not really into tittle-tattle. Times have changed.

The concept of Boris as vote-winner is unproven. True he has twice been elected Mayor in Left-leaning London. But you must look at these wins by looking at his opponent's controversial appeal. Like Boris Ken had his loyal supporters but the number of people who said "Anyone but Ken" far outnumbered those who said "Anyone but Boris". A good Labour candidate (Alan Johnson for example) would have beaten his namesake last time round.

"The idea of Prime Minister Boris appeals most to those who have the most jaded view of what politics can achieve for the country and themselves" in Ashcroft's report is brilliantly put and a bit depressing - though true. The "appeal" is identical to that of UKIP. And George Galloway. It's a "stuff you" reaction in difficult times - rather like the search for scapegoats for our troubles. "I Blame the EU and immigrants" say these voters - mostly without having a clue about the real causes of Britain's malaise. But when push comes to shove in the run up to a General Election most of these voters will return to the more conventional fold of the three main parties - they always do. And at that time they will see David Cameron - warts and all - as a far more credible Prime Minister than Boris Johnson. Because he is.