There's only one way that the Rolling Stones are going to restore their lustre now that we know the market for tickets to see them on their valedictory tour is soft. They're going to have to do something which they haven't really had to worry about since the 80s, which is to play really brilliant shows.
Round about Live Aid, when outdoor gig going became just another branch of the international leisure industry, audiences decided that they would give the biggest bands slack on the musical front as long as they made up for it in sense of occasion. We won't say that your playing is ropey as long as you persuade us we're seeing "the greatest rock and roll band in the world". It was a confidence trick.
The last time I saw them was around that time in the 100 Club on Oxford Street. They were doing one of their "back to the clubs" column inch grabbers. There were just a few hundred people in the place. Sight lines weren't a problem. The audience weren't distracted by threatening weather or jets going into Heathrow.
And you know what? They weren't all that good. They had grown so used to playing on a certain scale that they could no longer rein in the gestures to suit the fact that the audience were under their noses and not in a different postal code. Keith Richards and Ron Wood played like men watching each other's moves but not listening to the noise coming out of each other's amps.
I've caught live recordings since then and it doesn't seem to have got much better. Since Bill Wyman left it's gone the other way. This is their official YouTube channel's view of their opening in L.A. this week. Jagger's urge to sell the song has got in the way of his just singing it. Gwen Stefani does "Wild Horses" as if she's in the West End in some musical based on their old hits. They play "The Last Time" as if they're the only people in the world who don't know that it's all about that echoey old guitar lick and the clanging tambourine and not just another "will this'll do?" boogie vamp.
(This is where McCartney scored. He got younger guys in his band, people who'd grown up listening to his records. They knew how to reproduce them live better than he did.)
And it's all too fast. All of it.
Go back and listen to their great records, from their very earliest ones to "Start Me Up", and the magnificence comes from the slur, the implied threat of the drums, the tail dragging whip of the rhythm section, the feeling of something being reined in in case it got out of control, the sound of something being played slightly slower than other bands would dare.
Jagger at his best was not manically patrolling the apron of the stage as if terrified of losing your attention. He was standing there and commanding it. Maybe he's running up and down working like crazy nowadays because he knows that they don't sound right.
Whether or not Glastonbury turns out to be their last hurrah it'll be treated as such. They'll be in your living room where they won't be able to retreat behind their mystique. Between now and then they should see if they can rediscover how to rock. I'm actually not interested in "the greatest rock and roll band in the world". I'd just like them to be, as the kids say, any good.