"Who was here in '69?" asked Mick Jagger from the stage at the Rolling Stones concert in Hyde Park in London this month.
I found myself jumping up and down with my arms in the air shouting "Me Mick, over here, me, me …". I looked around at the crowd - a reported 170,000-strong - and saw that barely anybody had heard the question, and I could see nobody responding as enthusiastically as me.
All rather undignified really for a man of my advancing years, and I could tell my 20-year-old daughter thought the same by the sideways stare I got. But it was true. I had been there that day in 1969 when the Stones did their now-legendary "Stones in the Park" concert.
It was a Saturday, I had my final school exam - history - that morning. I was good at history and thought I had done well. A long summer holiday of fun and relaxation lay in store, followed by the exciting prospect of university in the autumn. But first it was the Stones.
Although my recollection has been dimmed by the passing years, July 5, 1969, goes down as one of the best days of my life: first time I saw the Stones live, first open-air concert, first time I felt like a young man, rather than a schoolboy.
Forty-four years on I noticed immediately how many of the crowd were much younger than me. But - and this really surprised me - they knew all the words of the songs. Each one belted out by Jagger, Keith Richards and company was a gigantic singalong, even the more obscure ones like You Got the Silver, Richards' lament/love song.
How could this be? Why would 20-somethings know the lyrics of a band of wrinkly, ageing rockers, old enough to be their grandfathers?
I decided, thinking on this later, that it was all down to the old business magic of brand durability. The Stones had achieved an enduring status for their music and their image by careful management of the brand for half a century.
Despite all the youthful rebellion and excess, and some early mistakes, Jagger and Richards were actually pretty good managers who understood the secret of their early success and were able to transplant it successfully across the generations.
And despite the anti-establishment image, the iconoclasm and the extravagance, the Stones were never anti-business or anti-capitalist in the way that punk rock or anarcho rock later became.
They wanted to be millionaires, because that's what rock stars were supposed to be, and they knew how to do it: through ownership of their back catalogue, regular release of new music, and above all through touring. In an analysis of what Fortune magazine called "Rolling Stones Inc" a decade ago, it was estimated that the Stones had averaged US$1.5 billion of revenue in the previous 15 years from live shows. Since then, and with the big mark-up in ticket face values they can command, that must be closer to $3bn.
They also knew how to delegate to serious business people. It might be Hot Licks on the outside, but behind that big red tongue it was all about cost control, sound accounting and revenue maximisation.
Those kids in the park, who could sing along word for word with me and Mick, were fans of one of the best examples of brand management and business acumen in the multibillion-dollar entertainment industry, as well as "the greatest rock and roll band in the world".