At the sound of the third chord, I let out a roar of recognition, lifted both arms above my head (quite an achievement when 170,000 bodies are pressing against yours) and started to bellow the words: “I was borrrn – in a crossfire hurricane . . . And I hoooowwwled at my ma in the drivin rain. BUT IT’S AAAALL RAHT NOW – INFACTITSA GAAS . . . ”

Endorphins fizzed through my veins. For the next 2½ hours I stamped, jumped and shouted my way from Jumpin' Jack Flash through to the encore.

Glastonbury wasn't the first time I'd seen the Rolling Stones. That was in 1973 at the Empire Pool in Wembley. I was 14 and had given over my life to debating who I loved best: Mick Jagger or Keith Richards.

And yet that concert was the most disappointing evening of my short life: though I pretended to my friends it was far out (man), I was secretly unmoved.

Then this summer, unexpectedly and slightly embarrassingly, I found myself having a profound religious experience involving becoming my 14-year-old self all over again – much to the consternation of my 20-year-old daughter, who stood disbelieving by my gyrating side.

Since then I’ve been trying to work out how come the Stones did something to me that their younger, less wrinkly selves failed to do four decades ago. Why was I so moved – especially as I don’t particularly like their music any more? I’m now a grown-up whose life is measured out in parents’ evenings and business meetings and so honky-tonk women seem pretty peripheral.

Age routed
Maybe it was glee at seeing age so successfully routed. It is hard not to be cheered at the sight of a man 15 years older than you strutting his stuff so convincingly.

And yet I don’t think that was it. At the time I didn’t look at Mick Jagger and think, “Gosh, you’re ancient.” Instead I thought: “Gosh, you’re Mick Jagger.”

This, surely, is what the Stones' 50 & Counting tour is about. The world's most enduringly successful group stays that way not by reinvention but by eschewing change altogether. The Stones flout the rules contained in every single success manual and invest their remaining energy in staying just the same.

The Glastonbury set was almost identical to the one they played 40 years earlier; the only difference was that I could actually hear it as the sound at rock concerts is so much better than it was. Better still, I could see them.

Not the real Stones – though I occasionally caught a glimpse of Mick’s green sequins and black feathers through the crowd – but a giant version on the screen right over my head, on which a brilliantly edited and filmed performance unfolded.

There they all were, ginormous and wearing just the sort of clothes the Stones ought to wear and playing Gimme Shelter just as it sounds on the 1969 LP Let it Bleed. It's true that you could also see the deep furrows on their faces – but those merely served to mark time and make the lack of any other change all the more remarkable.

The Stones' tour should be made into a business school case study on when change is called for – and when it isn't. Change is good if it means being better, faster, cheaper – if it leads to clearer sound and cleaner images. But in anything that touches our emotions, change is a very bad thing indeed. This applies to rock bands – and it applies to chocolate. The other day I bought an Orange Club biscuit and felt a similar surge of gratitude on finding it identical to the ones I used to have in my packed lunchbox.

Functioning memories
Equally, when I went to a Clarks shoe shop recently and found the original blonde desert boots with the same orangey stitching and white soles, I would have bought them on the spot, only my feet – like Jagger's face – seem to have collapsed and spread out and so they no longer fit.

We notice when the things of our youth are tampered with, as that was a time when our memories functioned perfectly. Every word of every Stones song is preserved forever in the aspic of my cerebrum – unlike, say, my new computer password, which never seems to get purchase at all.

The Stones wisely don't mess with our memories, unlike Bob Dylan, who spitefully and perversely performs his old songs as if defying anyone to recognise them.

Even for those of us who happen not to be global rock stars, there is no necessary virtue in change.

I just glanced at an interview with political scientist Anne-Marie Slaughter, in which she says proudly: “I have reinvented/disrupted myself every six to eight years.”

That sounds quite tiring to me. I’m going to think of Mick Jagger and continue to do no reinventing and no disrupting at all and see if life can still be a gasgasgas. – (Copyright The Financial Times Limited 2013)