The unwritten code that governs British public life is a strange mixture of keeping up appearances, hypocrisy, do-as-you-would-be-done-by and bastardised Christian ethics.  Some of its tenets are as follows.  Be considerate to other people, or at least pretend to.  Don’t tell lies – not least because, if you do, you may be found out.  Don’t have affairs (ditto).  Pursue ideals and ideas consistently, or seem to.  Don’t play the fool, because if you do so you risk being taken for one.  The spirit of Lord Chesterfield’s letters to his son is alive and well.

Boris Johnson is unique in our politics in breaking at least some of these rules nearly all the time.  That he does so has been drawn to public attention during the last few days, most vividly by Matthew Parris in the Times.  The latter portrayed the Mayor of London last weekend as an adulterer, a liar, a conniver in abortion, an accomplice in violence, a seeker of gagging orders, a serial underachiever, and a man bereft of political principle: a cynic in a jester’s cap who strikes comic poses while picking our pockets – who wants to have his cake and eat it.

ConservativeHome is an admirer of Boris (to the point of not usually referring to him by his surname, as is our practice with every other leading Tory politician) but concedes that this charge-sheet can’t simply be laughed off.  That Parris, a supporter of Remain, has not issued it before – and has clearly only done so now because the Mayor has come out for Leave – makes them no less so.  It would be easy for this Brexit-backing site to dismiss them for that reason.  It would also be evasive.  So let’s ponder their merit.

Anyone who glances below the line at articles about Boris on ConHome will know that not all Party members love him, like him, or even rate him.  Some see him, not to put too fine a point on it, as a joke in bad taste.  This is a reason to agree with Parris that the Mayor should not succeed David Cameron, at least as far as it goes.  It would be a bad thing for the next Party leader to be detested by a portion of it.  And there will always be an element which believes that Boris’s private doings render him unfit for public office.

But pause there for a moment: indeed, go back to where we started – to that unwritten code – and ask some questions.  If the Mayor is selfish, is he really unique, or even uncommon, among politicians in so being?  If he doesn’t always tell the truth, is that so unusual either?  Is he really the only person in British public life to have had an affair and, if so, should he really be singled out for it?  Is the only one to travel ideology-light?  Should he be punished for breaking the code rather than bending it?  This is the other side of the balance and should be weighed carefully.

There is a more solid case against Boris as a future Party leader and Prime Minister.  It is that both posts are unsuitable for somone who always wants to be loved.  As their holder, the Mayor would have to deal with Putin and ISIS.  Neither is especially prone to having their ribs tickled.  Boris looked out of his depth during the London riots of 2011 and occupying Number 10 would take him into far deeper water.  Those clunky fingers turn out beautiful copy for the Daily Telegraph, but do you really want them on the nuclear button?

But if there is a sturdy case against Boris there is also a persuasive case for him.  He has twice been elected Mayor of one of the greatest cities in the world.  He thus has the biggest personal mandate of any British politician.  That he has achieved this double in a Labour-leaning city is a gobsmacking achievement, and demonstrates that he reaches other politicians can’t reach – especially, perhaps, Conservative ones.  Follow him around in public for a bit, then follow another politician around, and you will swiftly clock the difference.

Furthermore, he has not messed up as Mayor, to say the least, and has been rather a good one, to put the point more strongly.  Crime is down.  The tube is being modernised.  A record number of homes is being built.  He beats the drum for London with oomph and makes the case for it with pizzazz.  He twinkled during the Olympics like a star.  He understands how to delegate and some of his appointments have been top-notch – Munira Mirza, Gerard Lyons, the late Simon Milton.

To be sure, some of them didn’t work out quite so well.  Some of the progress reflects wider trends, such as the fall in crime.  And it is always hard to tell quite where central Government’s role ends and the Mayor’s begins.  None the less, the claim that Boris is simply incapable of doing a major political job has been comprehensively debunked.  He has earned a shot at holding a Cabinet post.  It is not at all absurd to claim that, before too long is out, he could earn a shot at the top one.

That’s the point: could.  This man, whose “anchor is firmly secured in a kind of humane and cheerful moderation”; who “has some of the qualities of a great and inspirational leader” and who could even be “a rather brilliant Prime Minister”, is not a contender for the Party leadership at present, if only because no election is taking place, and he may never be one at all.  All those quotes, by the way, are from Matthew Parris (see here and here) – the very same author of last Saturday’s article.

They were all, I should add, very heavily qualified – subject to the kind of checks and balances largely absent from the piece in question.  They were also written before Boris came out for Leave.  You must make of that what you will.  My own take is that I am grateful to Matthew for providing me with an opportunity to write the truth about Boris.  How do I dare claim to know it?  Simply because we were reminded over the weekend that the Mayor prefers his friends to call him by his real name, Alex.

I don’t know Alex at all.  However, I do know Boris – and so do all of you.  But my indulgence of Matthew goes only so far.  At some point, the Mayor may be a leadership candidate in the final ballot.  If so, he will be up against Someone Else.  And while we know quite a lot about Boris we know nothing at all about Someone Else – what he thinks about the deficit; his views on social justice; his take on Brexit; his attitude to climate change; whether he is kind to his mother, animals and party members: indeed, we don’t know who he – or she – may turn out to be.

This being so, I see no reason to make up my mind about whether the Mayor of London would be a better prospect.  I will neither worship at the Temple of Boris nor violate its sacred groves.  For all I know, David Cameron will be in place as Prime Minister until 2019 or so – and, despite rising irritation at his tactless handling of his party, believe on balance that he should be. Boris’s fans want us to praise him; his enemies demand that we bury him.  But our attitude to Boris should exactly mirror his attitude to us: we should have our cake and eat it.