Timeless in its wisdom, the book Parkinson’s Law is of course famous for Parkinson’s law itself: that ‘work expands to fill the time available for its completion’. But scattered through the now 60-year-old book’s pages of tongue-in-cheek social science and cod-mathematical equations are remarks that lodged themselves deep in my thoughts when first I read the book as a young man. Stray observations keep resurfacing as being funny — yes — and flippant, I suppose, but these thoughts are more than flippantly funny: they contain too the germs of deep truths.

‘It is now known,’ wrote C. Northcote Parkinson, ‘that men enter local politics solely as a result of being unhappily married.’

And more than 40 years of close observation of political life have convinced me that unhappiness, personal frustration or emotional imbalance are among the principal stimuli to a career in politics. Fame is not the only spur: ambition may take root in a troubled interior life, too; and on this page I’ve elaborated before on my theory that politics as a career disproportionately attracts people who are a bit crazy, troubled or lost.

But in recent years I’ve made another discovery. An intense interest in current affairs from the viewpoint of spectator rather than participant is also a common indicator of a life going wrong. People who are in trouble mentally, in their careers or in their relationships, tend to develop strong opinions and feelings about the political scene, and to follow the scene with more intense interest than those whose lives are going well.

To the practitioners of politics first (and be clear that I don’t exclude myself from this analysis). Many years ago I wrote a book, Great Parliamentary Scandals, that took readers on a tour d’horizon of some of the more memorable falls from grace in British politics. Not all were deserved. Not all were historically important. But most involved colourful characters caught out in tremendously risky activities, inviting the comment: ‘Whatever was he thinking?’

When we look across the green benches of the House of Commons we are not looking at a representative cross-section of humanity but at a special subsection: men (mostly men) who seem prone to greater silliness and riskier judgments than the generality, yet who have chosen a career in which folly and risk attract far higher penalties in terms of public shame than if these men had chosen, for instance, to be greengrocers, actuaries or engineers. And for every disgraced politician you hear about there will be a couple more you don’t. The risks of exposure these men take are horrendous, of course, but they rarely exceed about 30 per cent. A probable two out of three get away with it.

But is it, you may wonder, simply that (say) a greengrocer who had become addicted to sending thousands of sexually suggestive texts to women he hardly knew and had no reason to trust, and who were half his age, would be of little interest to the national media? Would a booking clerk pretending to a façade of conventional married life while being secretly and busily homosexual make the front page of the Sun? No. An unsparing media spotlight may indeed exaggerate the impression that Parliament is an aviary for birds of bright plumage.

I’d counter with this: if politics is so unusually dangerous for oddballs, risk-takers and marriage-wreckers, shouldn’t that deter such types from seeking election? Shouldn’t Westminster contain a higher — not lower — than average proportion of prudent and risk-averse individuals? Yet I defy you to survey the 650 people who represent us in Parliament and tell me that they are less rum a bunch than the national average.

Instead the place is stuffed with precisely the type that any career adviser would warn to keep away from the spotlight. But you might as well remark that if you were a moth then in view of your species’ experiences you’d be especially careful to avoid flames. You wouldn’t.

So now to my second and newer theory. Not only are the political actors disproportionately off the rails, but so is their most attentive audience. My evidence here must be anecdotal, but it has struck me too often for coincidence that a friend’s or acquaintance’s swelling interest in the political scene has coincided with problems in his or her personal life.

I’m the kind of chap to whom people who know my contact details tend to direct random messages, often with multiple question or exclamation marks, with their views or questions on the passing political scene. These will be from people not themselves in politics or the media, and in theory disinterested: ‘What a wanker David Cameron is!!!’; ‘Can you imagine the catastrophe a Corbyn government would be???’; ‘What do you think of Boris’s chances?’; or ‘How can you possibly stay a Remainer and defend the fucking EU???’ Experience has taught me, on receiving such messages, to make discreet enquiries as to whether X has just lost his job; Y her boyfriend; or Z his reputation. All too often I will discover that the surfacing of strong opinions about the passing political scene has coincided with a period of turbulence in the individual’s interior life.

This column has not the space, nor this columnist the expertise, to investigate reasons, but they may be simple. A great deal of political engagement (particularly these days) is driven by rage, frustration or disappointment. Those inhabited by emotional responses to problems in their own private lives will find in politics unlimited opportunities to harness their anger and their sorrow.

If you read this magazine online, look beneath columns like mine on politics. There among the ‘online posts’ of readers you will find the extremes of violent or abusive language and thought that so tellingly point to troubled personal lives. If this is my audience then I’m drawn to a melancholy conclusion: columnists like me are just nutters who have found paid employment by writing for nutters. The rest of the world, meanwhile, cultivates its garden.