Keen to publicise an event whose sponsorship it now under-writes, The Daily Telegraph supplied full-on coverage of a session staged at last week's Ways with Words festival. Here, the 79-year-old Dame Penelope Lively and her slightly younger confederate Baroness Bakewell argued for the advantages of ageing. According to Dame Penelope, the 21st century is "a good time to be old". Uniquely in human history, there now exists a significant part of the demographic who are not only on the wrong side of 60 but have both health and faculties in working order. "Grey power," she grandly concluded, "is coming."

One hears this kind of thing quite a lot these days. Promoting his last-but-one novel, The Pregnant Widow, Martin Amis went so far as to prophesy an intergenerational guerrilla war, in which bands of furious pensioners would wreak a deadly vengeance on the profligate, idle and impoverished young. No doubt, in general terms, it is a good time to be old, and yet pronouncements of the Lively/Bakewell school have a fatal habit of ignoring the fact that one's attitude to the merits and de-merits of ageing is horribly subjective, and rests entirely on the age one has reached oneself.

And so, fetching up in literary London half a lifetime ago, I was appalled by the suspicion that its citadels were guarded (at any rate to my inexperienced eye) by a gang of leathery oldsters bent on doing favours to people with whom they had sauntered round Oxbridge quadrangles at about the time of the Two Cultures debate. Twenty-five years later, on the other hand, this judgment has undergone an 180-degree turn and I have a sneaking feeling that the place is swarming with imperfectly educated young whippersnappers who shouldn't be let out into the public prints for fear of embarrassing themselves.

There is no getting away from the futility of these generational rallying cries, for like many of the opinions which we imagine we have arrived at objectively they are mostly a matter of voting for your party. Going back to last week's symposium, one wonders only at its anticipatory note. Baroness Bakewell, for example, has spent the last half-century virtually drowning in column inches. For her, surely, "grey power" is already here.

Sociologists regularly point out that whenever anyone mints a neologism for a particular human situation, countless examples of contemporary behaviour instantly start conforming to its pattern, while a great deal of bygone activity is immediately caught up in its contextual net. Thus Joseph Heller's definition of "Catch 22" – a contingency in which Plan B can only work if Plan A is in place, later stymied by the discovery that Plan A can only be instituted if Plan B is up and running – explains the mid-19th century stand-off between the as yet unsuccessful Victor Hugo and his wary publishers. The former had told Hugo that if he could only make a name for himself they would publish any book he wrote. All very well, Hugo retorted, but he could only make that name if he were allowed to publish a book in the first place.

Certainly "the Murdoch Defence", which declared itself earlier this year in the course of the Leveson inquiry, now seems to have dozens of exponents. This stratagem, you will remember, consists of a supposedly all-powerful figure accused of wrongdoing trying to excuse himself on grounds of ignorance, and thereby exposing himself to a second charge of inadequacy. Inaugurated by James Murdoch, it rapidly found a second devotee in the shape of the Culture Secretary Jeremy Hunt, whose explanation for his adviser's shortcomings rested on an insufficient control of his department, and now, in the person of Barclays' Bob Diamond, it has a third.

To put the matter bluntly, all the evidence suggests that Mr Diamond ran his business with a microscopic attention to detail. If he didn't know that his underlings were fixing the Libor rate, then he jolly well should have done. It is the difference between being a crook or an incompetent. This may not sound much of a choice, but in the Murdoch Defence, damage limitation is all.

There is something rather comforting in the way that last year's rebel habitually mutates into next year's establishment figure, either by "revolting into style", to use the poet Thom Gunn's eloquent phrase, or succumbing to the calcification of spirit that undermines all but the most truculent ingrate in the end.

Even so, I was startled to find no fewer than three ornaments of the class of '77 revealing just how savagely their claws have been filed down. First we had the Clash's immortal Cold War anthem "London Calling" featuring as the soundtrack to a British Airways ad. Then John Lydon dropped some notably emollient remarks about Her Majesty the Queen, with whom he is said to "empathise". Finally, Paul Weller turned up in the newspapers in advance of his appearance at the Latitude Festival, extolling the joys of temperance.

Amid this middle-aged maturity, it was a relief to discover that the Stone Roses' Ian Brown had delivered some bracing remarks about the "witch" of Windsor. On the other hand, one couldn't help feeling that this gesture would have been slightly more compelling had the band not made several million pounds out of their reunion gig. Starveling resentment is always more authentic.