I see that Sir Paul McCartney is busy writing his first-ever musical based on the movie It’s A Wonderful Life. Will it, I wonder, be as brilliant as his Liverpool Oratorio, greeted at the time as if it was a work of genius only to end up in the Tinpan Alley oubliette?

I defer to nobody in my overall appreciation of Macca. He was astonishingly good in his Beatles days, and for a decade or so after the group’s breakup continued to write the odd catchy tune, not including Mull of Kintyre. But the oratorio, written in collaboration with Carl Davis and starring (if that’s the word) Dame Kiri Te Kanawa and Willard White, has not thus far entered the canon of great twentieth century music. It sold extremely well when it first came out, purely on the back of his name. These days, not so much.

It’s A Wonderful Life might, of course, be different. For a start, the script, if lifted from the movie, is virtually the definition of a feel-good story. And McCartney has the skill, and the experience, to play on our emotions. If he comes up with a couple of memorable melodies, he may even have a hit on his hands.

But there is something about old rockers. Though they tend, increasingly, to carry on rocking well into old age, they almost always have nothing new to say much beyond the age of 30. McCartney is an obvious example. It was John Lennon, no less, who said that his friend would never again write anything as good as Yesterday. As a judgement it was somewhat premature, but it gets truer with each passing year.

He is not alone in this. When did Mick Jagger and Keith Richards, or Pete Townshend, or Robin Gibb, or Benny Andersson and Björn Ulvaeus, or Ray Davies or Bruce Springsteen, or Bob Dylan, or for that matter Carole King, Norah Jones or Madonna, last write a hit song? I wouldn’t be surprised to learn that Adele has shot her bolt, and she’s only 31.

The pop music muse seems to fade after 15 years at most in the limelight, and then die off more or less completely. Whereas the great classical composers often got better, and more profound, in their later years, song-writers look to be born with a hit-by date beyond which they become their own tribute bands. They may not actually go pop! But the air gradually leaks out of their balloons.

I remember listening to Ray Davies being interviewed on the radio in New York in 2007. As the writer behind such timeless hits as Waterloo Sunset, Autumn Almanac, Lola, All Day and All of the Night and A Well Respected Man (the list goes on), he made the Kinks one of the original Sounds of the Sixties, and I admired him almost as much as McCartney. In the interview, he talked about a new solo album he was working on of which he had high hopes. It would be released as Working Man’s Café, with tracks that included You’re asking Me, Imaginary Man and No One Listen. It sold decently, mainly out of respect for the artist, but has long since vanished, as (already) has his 2017 studio album, Americana, released on the Legacy label as an homage to the music of his youth. Davies’s voice has held up well and he continues to come up with inventive lyrics. Somehow, though – and I know this is unfair – it feels like time-travel, unconnected to present events.

It’s the same with the Stones. If you look them up on Google, you will discover that they have released no fewer than 30 studio albums. So when the day finally comes when these great grandads of rock go to their final reward, what will they be remembered for? You’ve got it: the ten legendary albums recorded between 1964 and 1972, starting with The Rolling Stones and ending with Exile in Main Street. Jagger and Richards were aged between 21 and 29 when they wrote the tracks for these unassailable masterpieces. Today, in their mid-seventies, they couldn’t write a hit song if they tried, which by and large they don’t. More to the point, they couldn’t when they were in their forties, nearly a third of a century ago. If Jagger has had a muse since the mid-seventies, it is the dollar. Everything else is just performance.

A couple of days ago, on French television, I watched David Crosby, another luminary from Rock’s glory days, strutting his remaining stuff on Jimmy Kimmel Live, the ABC talk-show. Crosby is 77 and looks every day of it, with long, straggly white hair and a full-on 1970s moustache. He was promoting his documentary, the appropriately entitled Remember My Name, designed to remind us of the days, decades ago, when he fronted The Byrds and had his name on the door of Crosby, Stills and Nash.

It turns out that among the rival artists Crosby has the least time for is his near-contemporary, Jim Morrison, who died in 1971 aged 27. Morrison – whose grave in Paris’s Père Lachaise cemetery still attracts throngs of fans, not all of them elderly – didn’t stick around long enough to outlive his reputation. Is it possible that Crosby (like Roger Daltry, but without the irony) envies him this? At least the Doors frontman, who gave us Light My Fire and Riders on the Storm, didn’t have to come up with new hits when he’d rather put his feet up and and eat a runny egg. Reviewers are agreed that Remember My Name is both honest and compelling, but I have to say, with songs like Carry On and Déjà Vu playing in the background, it sounds to me more like an obituary.

Ah, but I hear you say, what about Bowie and what about Leonard Cohen? Didn’t they still have it in their, let us say, mature years? Let me admit straight away that I missed out on David Bowie. I was vaguely aware of his greatest hits, but I didn’t feel them. For reasons that don’t spring immediately to mind, Ziggy Stardust, in all his guises, passed me by. Even so, I would still argue that he was at his most inventive in the 1970s, when he himself was in his twenties and it will be the discs he recorded then that will live on after him. In his later years, for all his cleverness, it was mainly pastiche and painted faces.

Cohen was something else. Now there was someone who knew how to keep churning it out. His secret, if I am any judge – and at 70 I, too, am well past my best – was to keep his songs age-appropriate. He wrote for the young, the not-so-young, the middle-aged and the frankly one-foot-in-the grave lobby, and he covered each of them superbly. Perhaps it was his sepulchral voice that did the trick – that and his trademark Fedora. When on the album I’m Your Man, released way back in 1988, he sang about aching in the places he used to play, I was right there with him, and I was only 40 at the time. Decades on, he was the only artist, apart perhaps from Marlene Dietrich, who could make being 80 sound sexy.

They don’t make them like Cohen anymore. Or at least that’s what I think. But if Paul McCartney, a mere stripling of 77, can roll back the years and give us a fresh take on It’s A Wonderful Life, I will take off my fedora to him.