He actually pledged to give up stage-diving in March, did Iggy Pop. It's only May, and already that promise has been broken.

The man is the very embodiment of punk rock as he invites us all to go to hell and lobs his mic stand in a looping arc across the stage. It's a total mystery where he gets the energy to do all his baggy-limbed capering about, but he's doing it with the gumption of men a third his age.

Iggy raises a massive cheer for his first stage-dive of the night, precipitating himself into the crowd with gleeful abandon. He disappears for a few minutes, the only sign of his passing being a ripple of pumping limbs amid a cartoon-style dust cloud. Every time he bounces into the moshpit at the front of the stage, a nervous-looking roadie hovers over the Iggy-shaped morass, no doubt under strict orders to get him back onstage before the next verse starts. It looks like a thankless task.

"I want every single one of you up on this stage," he demands at one point, like a mischievous uncle. There are 5,000 people in the auditorium. About 30 people do make it up there past reluctant bouncers: they dance around and hug him, and he lets them do a bit of singing. One wild-haired and part-naked kid takes the opportunity to do a stage-dive of his own.

You get the impression that this is but a pale echo of the chaos conjured up at Stooges shows passim. He's not slashing at himself with broken glass or thumping himself in the face, for instance, but then, he is 63.

As you'd expect, there are a lot of ageing punks in tonight, faded tattoos highlighting sadly sagging flesh, their hair up as best it can be when there's only half of it left. They're generally got up in ways to make their kids cringe, and while they probably aren't slam-dancing with quite the vigour of their youth, most of them are sporting absolutely beatific expressions, as though they've arrived in some kind of punk-rock Asgard. It's quite sweet.

They're playing their 1973 album, Raw Power, tonight, leaving the show uncontaminated by weaker latter-day material. With it comes no shortage of energy; that would be impossible in the face of the sheer wall of blues-punk pulsating through the huge stacks of man-sized amps on stage. It's inescapable – they've got everything turned up to eleven; the kick drum, especially, is beating through my chest like an augmented heart. It's primal, and it's unutterably thrilling.

It's not about the Stooges tonight, though, it's all about Iggy. Trousers are at half-mast for the encore, when he bares his bum and waggles it at us. I'm quite a way away, but I think he may have offered us a dose of frontal nudity, too. Old age has barely tamed him – his antics may be a little less extreme than they were nearly 40 years ago, but as he wades into the crowd for a final, triumphal wrestle, you'd never know it.

He humps the wall as he leaves the stage, then pirouettes, flicks his hair and disappears for good. What a hero.