It is a sound maxim that it is political suicide to pontificate adversely about others, be they in politics or not, who share your particular weaknesses — even if this leaves an MP able to talk only about sugar-beet production in East Anglia.

During my brief sojourn in the House of Commons, one facet of life there that amazed me was how some members, even very senior ministers, openly led double lives and never had their indiscretions, which must have filled pages of the Whips’ black book, publicly mentioned, while others who strayed a few inches off the straight and narrow and were hung out to dry.

The behaviour of the Liberal Democrat MP Mark Oaten — in his capacity as a private individual — should be a matter between him and his wife. It is not always realised that most apparently homosexual men are, in fact, bisexual to varying degrees and have had heterosexual experience. This makes nonsense of the oft-repeated comment that a man is unlikely to be homosexual because he has a family — many are keen family men.

However, Oaten has shown neither political nor social acumen — having been rumbled by a rent boy, it was lunacy not to keep a low profile — and that has important implications. For whatever reasons, many of my male patients became regular clients of prostitutes and were rewarded with absolute discretion.

Conversely, most of my gay patients who used the services of male prostitutes deemed it foolhardy in the extreme to return more than once. Male prostitutes didn’t seem to have the same working code, and many were treacherous.

Illicit sex with a prostitute is said to satisfy three drives: sex, aggression and a love of danger, motivating forces that are not unknown to politicians. Journeying along the corridor of power leading to Downing Street is like traversing a hotel corridor studded with tempting rooms and other diversions along its length. To reach No 10, or any other great office of State, successful politicians are likely to be testosterone-rich, goal-orientated risk-takers — why else would they have left safe jobs? — and rather more ruthless than their contemporaries.

Politicians are likely to have enormous reserves of energy, which some may dissipate in the House of Commons library by toiling away at their next project, or by burrowing through a mountain of papers as they prepare for a committee meeting. Conversely, many fail to control their less worthy, but still strong, more easily satisfied desires of pre-parliamentary days, and be lured into some of those secluded rooms leading off the corridors of power.

The men — and now as often, presumably, women — who reach the top are not likely to have a type B personality — laid back, phlegmatic, nonchalant, unambitious and calm. Harold Macmillan, so Maurice, his Cabinet Minister son, once told me, noted that a problem for prime ministers when choosing their team was that a politician’s prowess was proportionate to his sexuality. Cut out the risk-taking, testosterone-powered colleagues and the country would be denied some of the best available leadership, just as surely as Sunday tabloids would be deprived of their lead stories.

Politics, like the rock world, attracts groupies. Recently an ageing pop star recounted how he and his band judged groupies. Like cattle dealers grading beasts in the market, the band settled on whom they would befriend that night. The lead singer probably had first choice.

I wouldn’t have believed that the same principle applied to some politicians until years after I was in the House, when a distinguished statesman told me that, like most public speakers, when starting a speech he looked round the room to make contact with the audience. But in his case it wasn’t only to empathise with them, but to scan the room for a likely candidate for drinks in his room later. Power is so powerful an aphrodisiac that he usually succeeded in finding someone to share his bed, as well a bottle of champagne.

Risk-taking, thrill-seeking politicians are not a new phenomenon. Wellington, Nelson, Palmerston, Gladstone, Asquith, Lloyd George and many others behaved in ways determined more by hormones than prudence or intellect. Modern society would not have tolerated them, but without their individuality, our history would have been much less colourful and we might never have achieved victory over France and the imperial might of the 19th century.

The popular belief is that sexual impulses, whether approved or not by society, are likely to have been inherited or acquired so early in life that whether they excite credit or blame, it is debatable whether they are caused by nature or nurture. Equally it is believed that however an individual’s sexual inclinations have been acquired, he/she still has the ability to control them.

Anthony Storr, an Oxford psychiatrist whose teaching was characterised by its good sense, suggested that one of society’s troubles was that elderly people tend to become self-righteous. By the time men are old enough to be in a position of influence, most had forgotten the strength of their sexual drive when younger. He added: “Sexuality is an impersonal and extremely powerful instinctive drive that seeks expression irrespective of the conscious will of the individual . . . Those men who claim to be able to control it entirely and suppress the expression of sex, while they are still in the first half of their life, are actually undersexed.” His opinion reinforces my own experience, derived from 23 years working in a VD clinic, that reformed rakes do exist, but not until age has diminished their sexual capacities is this reform accomplished.