So Boris has finally decided to run for Parliament at the general election next year.

I confess I’m surprised. I was quite confident he would realise the limited horizons parliamentary life will offer him and instead decide to run for a third term as Mayor of London knowing that he could comfortably beat all the likely Labour contenders.

I had assumed he would then retire, go round the world earning gazillions from speaking tours, write books and front endless television documentaries on everything from the decline and fall of Ancient Rome to the value of tall buildings in the modern megalopolis. He’d be in his element and if he tired of all that he could edit the Daily Telegraph or the New York Times.

So I was wrong. But I still think his decision is odd. Remember he has already sampled the House of Commons. He was MP for Henley when the chance came for him to stand for Mayor and it didn’t take much to persuade him to quit and try his luck. His first term in parliament had not been distinguished. He was fired by Michael Howard from his shadow education brief and forced to apologise to the people of Liverpool for ill-chosen remarks in a Spectator leader of which he was then editor. The chance to leave all that behind to stand for Mayor would have been irresistible.

But more to the point, assuming he does get back the Uxbridge seat vacated by John Randall, which despite his protestations is a fairly safe bet, he surely knows it will not be the cakewalk that some ignorant commentators assume.

Whatever they say publicly, neither the party leadership nor rank and file Tory MPs will rise up with one voice to hail their saviour. Far from it. Private Eye ran a cover a few weeks back which showed an electric chair below the headline “Cameron Finds Safe Seat for Boris”. That’s, frankly, more like it. To the current crop of Tory MPs Boris is a rival and any move on his part will be treated as a declaration of war. Boris undoubtedly has his supporters but Michael Gove, now installed as Chief Whip is certainly not one of them.

There is already no love lost on that score. And Boris is not a natural team player. Were he to lead the party he would find the daily grind of prime ministerial life stiflingly tedious.

Three other reasons make a Johnson leadership bid less than likely to succeed. When asked, Conservative voters invariably say they like him, they enjoy his speeches, he’s relentlessly positive but they wouldn’t want his finger on the nuclear trigger. And he knows that among Tories he comes a clear 12 points behind Theresa May as their preferred choice if David Cameron is run over by a trolleybus. Last but not least, he knows that if, however they do it, the Conservatives emerge in government after the election, the party which does not like Cameron will nonetheless not defenestrate him, leaving Johnson marooned for several years while other contenders circle.
The irony is that Boris could almost certainly win a third term as Mayor.

Dame Tessa Jowell, much loved and highly competent, is the Labour frontrunner but she is an unrepentant Blairite and by no means certain of nomination by a London Labour party which is way to the left of its leadership. Lord Adonis is hugely talented and would do the job brilliantly but has very little profile. Neither David Lammy nor Diane Abbot command much support outside the party and Sadiq Khan, while a senior minister in the last Labour government, does not have much of a popular following.

But Johnson has apparently made his decision. He will make a splendid Conservative Party Chairman, tub-thumping his way around the country and delighting the rank and file along the way. It is the job the next, or even the current, leader may well give him.

But Boris’s finger on the nuclear trigger? Just think about that for a few moments and then make up your own mind.