Are we really all grown up now when it comes to sex and politics? Last week it turned out that Ken Livingstone, the mayor of London, has had five children by three different women. His response was to tell us that the London electorate was far too blasé to care about this sort of thing.

“I don’t think anybody in this city is shocked about what consenting adults do,” he declared. “As long as you don’t involve children, animals and vegetables, they leave you to get on and live your own life in your own way.” This is to flatter his voters as the kind of urban sophisticate for whom anything as old-fashioned as love children doesn’t really register on the radar. The rest of the country is left to reflect on the kind of activities with root vegetables and family pets that might shock a Londoner.

In fact, as Livingstone knows, there is a good deal of difference between being shocked and being unable to talk about much else. For most of the people I know, Livingstone’s home life is about a hundred times more interesting than his affordable housing policy.

Not to put too fine a point on it, these revelations were meat and drink to most social gatherings in the capital. Guests at dinner parties had only to say: “What do you think about Ken, then?” for their interlocutor to guess that they were not talking about his poll ratings.

His office bravely countered: “What Londoners want to discuss in this election is transport, crime, housing, good community relations and the environment.” Hah. What Londoners wanted to discuss, at least for a day or two, was the mayor’s girlfriends and his nice-sounding son and daughters.

Which is not to say that Livingstone will be harmed by these revelations. The BBC’s Andrew Hosken, whose forthcoming book, Ken: The Ups and Downs of Ken Livingstone, prompted the mayor’s confession, went out of his way to say that his subject was not guilty of hypocrisy.

You hear that quite a lot nowadays. The argument seems to be that so long as politicians do not set much store by the importance of marriage, they can’t be caught out by revelations of adultery, extramarital children or problematic activities in public lavatories.

I don’t quite buy that myself. Double standards are better than none. You can quite legitimately say that you approve of marriage and stable relationships as being in the best interests of children and society – and indeed want the tax and benefits system to encourage them – and still be unable yourself to be strictly monogamous. Being incapable of living up to your own high ideals is not a reason for not having ideals at all.

The thing about Livingstone’s affairs is that they do not seem particularly out of character, given his – how to put this? – demeanour. What had seemed rather odd was the idea that he had waited until the age of 57 to become a father.

Actually the most remarkable aspect of the news was that the women concerned had not seen fit to share their recollections of their affairs with Livingstone with the wider public before now. It is that rare reticence, that refusal to cash in on their past, that is so extraordinary.

Indeed it was shared by the first and only Mrs Livingstone, who could have got a great deal of money for her thoughts about being married to Ken during his Greater London council days, but apparently turned down all requests for paid interviews. Respect all round.

And, as luck would have it, Livingstone’s Tory opponents are very unlikely to take a censorious view of such things, preferring, like him, to inhabit the foothills of notoriety rather than the high moral ground. Indeed, just as Livingstone was unburdening himself, a magazine interview appeared in which his mayoral rival Boris Johnson shyly confirmed to Janet Street-Porter that he had taken cocaine as a student and had smoked cannabis before university.

This is the new, pre-emptive confessional culture in which politicians decide it really is better to get the dirt out themselves than wait for someone else to do it. It’s like that in America. When Eliot Spitzer, New York’s disgraced governor, resigned after admitting to using call girls, his successor Donald Paterson lined up with his wife Michelle to confess to a string of past extramarital flings before starting the job. That cleared the air.

Johnson hardly needs to do the same. His private life sometimes resembles one of those Mies van der Rohe buildings in which the inside is perfectly visible from the outside. His affairs, beginning with the relationship with his present wife Marina, which ended his first marriage, have been the stuff of interested comment for years.

And if Johnson cannot boast illegitimate children, it is for the unfortunate reason that one was aborted. The subject on which he and Livingstone see eye to eye is the desirability of commentators sticking to what Tony Benn calls the “ishoos” rather than the candidates’ home lives. Rather like Livingstone’s previous Tory opponent then, Steve Norris, whose pudding face belied his startling libido.

I wonder, though, whether there isn’t some sort of congruity between the fact that Ken and Boris are the only men in British politics whom you can refer to by their Christian names, confident that people will know who you mean, and their notable testosterone levels.

Being morally good isn’t part of their particular package. People respond to them because of, not despite, an element of raffishness in their make-up. It’s part of what makes them if not admirable then at least distinctive and not boring.

Yet it is fatal for bland politicians to try to be less bland by bragging about their sex lives. Take Nick Clegg’s admission to GQ magazine that he has slept with up to 30 women. It didn’t make him less boring; it made you think: oh please, let’s not be embarrassing as well as dull. Some people are just better off inside the closet.

And let’s not get carried away about the new transparency. Livingstone has been belatedly candid about his illegitimate children. He is far more coy about the donations that he receives to his campaign, which are all funnelled through the London Labour party.

If we want to know whether property developers helped with his funding, we shall have to wait for three months after the election to find out. The era of openness has, alas, some way to go.

India Knight is away

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