11/10/2012 07:58 BST | Updated 10/12/2012 05:12 GMT

'Borismania' Reveals Tory Doubts - But Is Boris Really a Credible Future PM?

David Cameron was always going to have trouble with his party. His early leadership - the hugging of hoodies and huskies, boasting about being the "heir to Blair" and calls to "let sunshine win the day" - wasn't exactly reminiscent of the Thatcherite glory days.

Many of the traditional Conservative concerns, particlarly around immigration, crime and the EU, were marginalised or ignored. The emphasis was all about modernisation: creating a new brand for a toxic party. Much like Tony Blair and Labour in the 1990s, the impression given by Cameron was that the Tory grassroots were a hindrance, rather than a help.

Unlike Blair, however, Cameron failed the ultimate test: he didn't win. Against an extraordinarily unpopular prime minister and a discredited government, against a backdrop of recession and fiscal mismanagement, Cameron failed to deliver a Conservative majority.

The rest, of course, is history: the coalition, the compromises, the gradually increasing frustration within the Tory Party.

Which is why, after just two years of (mostly) Conservative government, Tory eyes are beginning to look towards Boris Johnson.

Unlike Cameron - unlike any other Conservative in the last 15 years - the Mayor of London is a winner. To get elected once in a Labour-leaning city is no mean feat. To do so twice is a very impressive achievement indeed (as is not totally cocking the job up in between).

It is highly unlikely that there will be a blond coup this side of the election. Boris isnt an MP (although he could become one pretty quickly). And Cameron is a tough leader, especially when he's backed into a corner. The Cabinet is loyal - remarkably so, given the concessions of coalition. There probably won't be enough anti-Cameron momentum to unseat him before 2015.

But the very fact that the party is in the grip of 'Borismania' reveals significant Tory doubts. If Cameron was thought to be in with a good chance in 2015, why so much speculation about a potential successor? Are some Tories - the ones most enamoured with the London Mayor - already mentally preparing for opposition? Or perhaps for an attempted coup after the next election, if we end up with another hung parliament?

As well as being a winner, Boris' personal appeal is huge. He is witty, charming and slightly buffoonish in a way that makes him appear perpetually benign. Far from an out of touch, callous toff, he is seen as a man of the people. How else can we explain huge crowds chanting his name in Hyde Park?

But therein lies the first danger. Mayor of London is nothing compared to being Prime Minister. Someone like Boris - viewed as more of a celebrity than a politician - can get elected Mayor, and do a decent job of it.

Is he credible enough, though, to represent Britain at an EU treaty negotiation, or at the UN Security Council? There is the danger that, although he'd undoubtedly be very popular, he wouldn't be taken seriously.

Likewise, is he the man we'd want in Whitehall directing the response to, God forbid, a major terrorist attack?

Disgruntled Tories should also think about policy. Would we get the proper conservative Boris, who would give us an EU referendum, get tough on strikers and slash the top rate of income tax? Or would we get liberal Boris, supporting a living wage, gay rights and an amnesty for illegal immigrants?

Are his current views sincere or, as cynics would suggest, clever populism designed to appeal simultaneously to the party faithful and the supporters he needs in the capital? Does he, in fact, believe in much at all (other than himself)?

Would he be able to make the tough decisions? He wants an EU referendum, but what would he do if Britain voted 'out'? Has he thought about it, or is it just reckless pandering? What other spending would he cut - or taxes would he raise - to pay for his £30 billion island airport?

Those are a lot of questions, admittedly. But that is because there are so many questions left to answer. Boris should not be the default choice to succeed Cameron, whenever the latter's luck runs out.

We have very little idea about what Boris truly believes, or whether there is much substance under that blond mop. And regardless, does he have the right character for the job?

If he gets close to the Tory leadership, the scrutiny will be fierce. It is all too likely that the answer to that final question will be "No".

Conservatives should save themselves some pain, and look elsewhere. Speculation about Boris may be a great diversion now, but he isn't the future.