It’s a truth pretty universally unacknowledged – but for all that, blindingly obvious once you’ve been told by One Who Knows – that the world is ruled by a sinister cabal of deeply egotistic – and, by extension, viciously bigoted – individuals. I’m not referring here to the usual suspects – I know there isn’t a Jewish conspiracy, because I’ve never been invited along to any of its meetings, any more than I have to those of the so-called establishment, and since my Wiki entry fingers me as both a Jew and an arch-establishmentarian, I know that at least these things must be true.

Nor, indeed, is this a conspiracy of the believers against the secular, the ugly contra the lovely, lizard-paedophiles averse to… everyone, or the rich versus the poor. As to our fates being determined by some weird historic determinism, whereby humanity “realises” itself through successive class antagonisms... Nope, sorry Jezzer. Far from being wreathed in false consciousness, the cabal I’m talking about hide in plain view – and perhaps the best way I have of getting you to eat the proverbial red pill, and so see for the first time the true horror that enfolds you, is for me to describe a group of these evil svengalis I saw only yesterday evening, outside a pub in Mortlake, south-west London.

True, they aren’t an especially metropolitan phenomenon – but can be found anywhere human society tries to flourish. Nevertheless, there is a certain kind of affluent-but-slightly-quirky suburb, exemplified by Mortlake, and often featuring mean-featured little Victorian villas, that seems to attract them. There they were: two women sporting boldly patterned pregnancy dresses, their men folk in khaki cargo shorts and collared T-shirts. All were talking animatedly – one of the men was actually stroking his jazz beard as I hurried past, my face averted. I refer, of course, to people in their 40s.

Yes: forget whatever ologies you may have studied along the way, demography is the only science that matters when it comes to the harsh terms of everyone’s existence (everyone who isn’t currently aged between 40 and 49, that is), for this is the cohort that has it all. St George of Orwell said “by the age of 50 every man has the face he deserves” – but the truth is, rather, “by the age of 50 every man and woman has the fate he or she deserves”, because, let’s face it, with one or two exceptions if you haven’t cut the mustard by then it’s cress sandwiches all the way into that perfect picnic spot: your grave.

Yes, yes, I know: for a long while now it’s looked as if our main problem was the bizarre demographic bouléversément that’s happened in the past 70 very odd years. I’m not the only Nytol-addled Nostradamus to have pointed out that if current trends persist our few remaining young folk will, soon enough, be crushed to death beneath the huge prolapsed denim-covered collective arse of superannuated baby boomerdom. Nor have I been alone when it comes to bemoaning the talentless hipster culture we’ve bequeathed our children – we’ve all seen it happen: the once proud artistic avant gardes of western Europe plummeting through clouds of frothy coffee, down into a brownish gloop comprising one part “crafted” gin to three of moustache wax.

If Johnson appears decadent, it’s because he is channelling his own inner 45-year-old

While there were still some baby boomers left in our 40s, I thought we were the problem – but now I know the hideous truth: it doesn’t matter that David Cameron turned 50 a few months after leaving office, or, for that matter, that Nick “Bend over for Zuckerberg” Clegg reached that noble age early the next year – the point is: there are always more ready to follow them: dead-eyed thirtysomethings on the verge of becoming the true Illuminati! Yes, yes, I know: the current prime minister is 55 – but if he resembles an amoral and Struwwelpeter-haired puppet, it’s because he is one, manipulated by Dominic Cummings (47). And if Johnson, with his bellowing, pants-down antics, also appears decadent – in the true sense of aping the mores of 10 years past – it’s because he is indeed channelling his own inner 45-year-old.

Yes, those in their 40s have the swaggering self-confidence of people-who’ve-arrived, but far from this destination being the dark wood that inspired Dante to deep spiritual reflection, theirs is the smugness of those whose position in the hierarchy is well established, plus the antics of the boorish teenagers they so clearly remain. See them paint their faces and go to Glastonbury! See them disappear into a k-hole while actually eating Special K to ease their costive and ageing bowels! Moreover, with advances in the technology of human fertilisation, fortysomethings are now able to reproduce themselves – which accounts for the creepily philoprogenitive group on the riverside at Mortlake.

When I swallowed the red pill and saw them for the first time in all their old-young hideousness, it occurred to me: is it only this generation of 40-year-olds that’s quite so repulsive (and quite so powerful), or has this Masonic order of the middle-aged always been so smugly unreflective? True, the current incumbents are a grisly bunch – but what can you expect of people whose cultural hinterland has been formed by the likes of Coldplay and Radiohead, and who came of age listening to the peculiar banging whine of dial-up internet connections, as, feverishly, they waited to play some dumb and wholly unrealistic computer game?

Granted, I do have this obvious partisanship – and there’s also a further objection to my thesis: that I approach the issue with a perspective warped by my own 57 (and rising) years. But let me reassure you: when I recall how smugly self-satisfied I was in my own 40s – and how convinced I was of the importance of me and my fellow quadragenarians, well, I can tell you: I feel like giving that fellow a few sharp slaps in his metro-moisturised face, until it shines like a baby’s bottom. Or, alternatively, like the face of David Cameron, who, as I believe I may have made clear, is the leader of the fortysomethings’ revolution, and whose inappropriate Chelsea boot heel we’re all still being ground beneath.