IT'S true. Iggy Pop has kind of “gone off” rock’n’roll and he admits as much in the liner notes for new album Free.

“I began to recoil from guitar riffs in favour of guitarscapes,” he writes and the record — a more laid-back affair with plenty of trumpet — proves the point.

Perhaps that’s why tonight’s gig from the usually topless godfather of punk is being billed as part of the London Jazz Festival. And he keeps his shirt on.

The former Stooges frontman may be leading a different band, but Iggy is such a star performer, even at 72, that it never really matters what he plays but how he plays it. Seeing him perform in the clinical environs of the Barbican is a bit like lighting a firework inside a glass jar.

So while big hits The Passenger and Lust For Life don’t feature, the charisma of Iggy’s diminutive limping presence and trademark gravelly voice as he brings his latest album to life is captivating to behold.

He ambles across the stage as he sings Sonali and the humorous James Bond before sitting on a stool to begin a brilliantly performed Glow In The Dark, which ends in a crescendo of brass, bass and drums.

Those hungry for nostalgia are satiated with three from 1977 album The Idiot — Sister Midnight, Mass Production and Nightclubbing — as well as The Stooges’ Death Trip, which sees Iggy singing in the stalls. Many an adoring fan leaves their seat to get a closer look.

The second half includes Five Foot One and Run Like a Villain, before finishing with a rewritten cover of Chop Chop Chop from Sleaford Mods that relates more to Iggy’s rock’n’roll lifestyle.

“Thank you so much, you are my friends, eh?” he says at the end and even threatens to take his shirt off. But he decides against it. What a tease.