Is Boris Johnson's U-turn worth the risk? Machiavelli might have seen the flaws

So far Boris has led a charmed political life (PA)

Boris Johnson’s confirmation that he will stand as a Tory MP at the next election must, despite his repeated denials over the years, be one of the least unexpected or remarkable political announcements in recent years.

Put it this way: what good reason would the maniacally ambitious, Machiavellian, potential Tory leader have not to stand for Parliament?

But Mr Johnson’s decision is not, as some commentators may suggest, a threat to David Cameron, who sanctioned and even encouraged the plan at a private meeting earlier this year.

The reason is this: if Boris is to have any hope of succeeding Mr Cameron after the election he will need to be – and be seen to be – a loyal and active campaigner in the run up to 2015.

If he isn’t and the Tories lose he will be blamed by the Conservative Parliamentary party and will never even make it to the ballot of the wider party membership.

So Mr Cameron gets Boris inside the Tory tent and singing from a hymn sheet set by Lynton Crosby, who masterminded Boris’s own victory as Mayor of London.

And if Mr Cameron does defy electoral odds to win an overall majority at the next election there simply won’t be a vacancy for the top job.

Mr Cameron will then be free to appoint the Mayor to whatever Cabinet post he thinks will do most damage to his personal credibility and neutralise him as a future leadership threat.

So if the Tories win the general election in 2015, we can look forward to Boris Johnson the Local Government Secretary – of which he has experience – or perhaps a spell as Health Secretary.

And if the Tories lose, the pressure for Mr Cameron to resign will be overwhelming, regardless of whether Mr Johnson is an MP or not.

The Prime Minister will quickly fall on his sword, take to the international lecture circuit and probably care little whether it’s Boris, Theresa May or some other unfortunate who has to lead the party for five years in the wilderness.

But even then, Boris is far from a shoo-in for the leadership. So far he has led a charmed political life but he has skeletons in his closet that would come under intense scrutiny in any future Tory leadership campaign and which might make the predominantly elderly Tory membership think twice about the blond bombshell.

For a start he has sired two children outside his marriage, with two different women. One, now a four-year-old, resulted from an affair with the art consultant Helen Macintyre. Then there was the affair with the journalist Petronella Wyatt, which resulted in one abortion and a miscarriage.

On both occasions Boris’s long suffering wife Marina, the mother of his four other children, threw him out of the house. Boris, meanwhile, lied about the affair with Ms Wyatt (including to the then Tory leader, Michael Howard), describing reports of their relationship as “an inverted pyramid of piffle”.

When Ms Macintyre sought an injunction on behalf of her daughter to prevent details of the child’s conception becoming public, the High Court refused.

The judges ruled that Johnson had achieved a “level of notoriety” in his philandering and that fathering two children “goes to the issue of recklessness … relevant to both his private and professional character”.

Then there is the issue of his dismissal from The Times for making up quotes, and the existence of a tape recording where he agreed to supply a friend – later convicted of fraud – with the address of a journalist whom the friend wished to “beat up”.

“You’re a nasty piece of work, aren’t you?” asked the television presenter Eddie Mair, in an extraordinary interview in which he catalogued all of the London Mayor’s past indiscretions.

All that may ultimately prove too much baggage for Mr Johnson to overcome. But as a maniacally ambitious, Machiavellian potential Tory leader, he thinks it’s still worth a shot.