Circumstantial evidence leans against the notion. David Cameron is posher, smoother and a lot richer than the Hebridean crofters who brought my father into the world. If he were of our family, cousin Dave would certainly be the first in a thousand generations, as Neil Kinnock might say, to go to Eton.

Yet then I study Mr Cameron and I wonder if our link has less to do with kith and kin and more to do with the fact that we are both basically spin- doctors. This struck me most forcefully in his TV debate with David Davis, his fellow leadership contender. It has been said that David Cameron is the new Tony Blair. But watching Mr Cameron trying to soundbite his way through the debate, it was clear that Mr Cameron is not remotely in Mr Blair’s league. Far from being the new Blair, he may actually be the new Alastair Campbell.

He knows how to craft a line and put it over. He has a feel for what tickles the media’s fancy, what makes a story and how to get it up as a headline, what combination of action and demeanour keeps the photographers happy. He knows how to take a line of attack against him and turn it into a line of attack against his attackers. These are skills all press officers deploy from time to time. And every leader in the media age needs this kind of professional support.

There were plenty of times when Mr Blair would take my advice. But not for one second did I ever imagine I could do his job, let alone do it better than he did. I might have thought I did my job better than Messrs Major, Hague, Duncan Smith and Howard did theirs, but I always knew that their job was tougher. I’m not sure that Mr Cameron appreciates the difference.

Mr Cameron gave a classic example of the spin-doctor’s art of trying to turn a weakness into a strength when challenged by Mr Davis over the lack of detailed policy he had put forward. He summoned up all the passion he could muster to say why it would be stupid to set out detailed policy this far from a general election. His supporters applauded. But those of us who can spot a “defensive line to take” a mile off could see that it was a piece of spin to give political justification to a policy vacuum born of the fact that he had not thought through the issues beyond the soundbite level. “What do we want? No policy. When do we want it? Dunno.” Leadership it is not.

The comparison with Tony Blair is at its most superficial when it relates to policy and strategy. Mr Blair, Gordon Brown and others spent years working through the substantial policy and positioning changes the Labour Party needed to take. When he became leader, it was clear Mr Blair was a naturally good communicator of those positions. But it was the positions that mattered. Mr Cameron is OK at presentation but he has nothing to present other than being a presenter. What have the public learnt about him — that he probably took drugs, he can make a speech without notes and he can get out of a car as elegantly as Princess Diana. None of these requires special leadership qualities.

But since his triumph at the Tory conference, he has been coasting, playing safe when, had I been involved in his campaign, I would have been pressing him to go deeper into real policy. Instead, if anything Mr Davis has been making the running on policy. And once Mr Cameron had a presentational setback at the TV debate, I sensed he had little strategic base to draw on.

It is almost certain he will win. But I have seen enough to think he will be a good target for Labour. He wasn’t put under much pressure in the TV debate but when he was, he didn’t much like it. His Commons response to Ruth Kelly on the Education White Paper was poor. I see no parliamentary skills to worry Mr Blair or Mr Brown yet. His stance on terror, putting him on the side of civil liberties against the police, is a strategic error that won’t easily be undone, as is his deal on Europe with the hardline sceptics. Being in hock to Bill Cash et al will damage him in Opposition. It could destroy him, not to mention Britain’s relations in Europe, if he won power.

It shouldn’t be surprising that he feels more comfortable with spin than substance. He was Norman Lamont’s spin-doctor during Black Wednesday. He was a PR man for a TV company, and you can’t get much more spin-doctory than that.

There may be those who say there is a bit of double reverse spin at play here. First, it is said I am a friend of David Davis and this article may be seen as an attempt to assist him. I suspect my help would come somewhere after bird flu in Mr Davis’s list of desires. Secondly, some may say that in attempting to present Mr Cameron as an attractive target for Labour, I am revealing deep-seated fears about him. But as a newspaper commentator said recently, just because I say something doesn ’t mean it’s not true.

I know Mr Blair and Mr Brown well. They have strengths and weaknesses, but the strengths outnumber the weaknesses. I would put their PR and presentational skills fairly low down the list of other formidable strengths. From what I’ve seen of Mr Cameron I would put PR and presentation skills top of a fairly short list.

Someone canvassed after the first of the Tory hustings said that the two contenders would make a great dream ticket. Perhaps that should be Davis as leader and Cameron as his spin doctor.

Times Recommends

• Treasury needs a new golden rule fast
• Testing doctors is no magic cure
• We must cry out for the poor