Sometimes you’ve really got to step outside the indie bubble. Turns out, in the Serious Music World, when you arrive at a concert an hour after it’s scheduled to start, you’ve possibly missed some of the stuff you were supposed to review.

Another effect is that, when I arrive late and walk into the middle of a middle-aged man on stage playing an apparently tuneless barrage of notes on a soprano saxophone, the first reaction is one of mirth. It just seems utterly preposterous. Given a few minutes to sink in, though, and Evan Parker delivers one of the most stunning musical experiences I can remember. A master of circular breathing, his set is one continuous stream of noise, simultaneously unchanging and non-repetitive; microscopic musical figures linked together to create a thorny whirlwind of sound, ultra-fast scales with screeching overtones providing a train-brake descant. Almost like a computer vomiting out every note in its media library a millisecond at a time, there’s a huge, confusing but enveloping sound being exorcised from his sax.

When Tom Jenkinson (pictured) returns to the stage to duet with Parker, the crowd, unsurprisingly containing many more dreadlocked stoner-types than you’d expect at your average South Bank free-jazz show, go a little ape. Anyone who’s seen Jenkinson in his day job as Squarepusher will know that he’s more than a little tasty on the ol’ thumpstick, but whereas the solos on his spasmodic electronica can seem like a Bill Bailey sketch on slap-bass muso nonsense, tonight his fingers rarely wander anywhere near funk, and the set is all the better for it. It’s also genuinely startling that a man with this extreme level of technical skill is successful in a field of music not always related to what he clearly excels at. It’s hard to convey just how gifted he is.

Their improvisation starts by evoking images of the creepiest, most menacing weather imaginable, both instruments embroiled in a low-end flurry, texture and rhythm prioritised so much over melody and cogent tonality that notes are stripped of their individual identity, sublimated to a collective stream. Jenkinson treats his bass more like an advanced tuned percussive instrument than a guitar, making it hard to remember that, give or take a few strings, this is the same instrument that Kim Deal plays, such is its removal from its orthodox role. That said, when the bass does take a more traditional supportive role, with Jaco Pastorius-esque harmonic planes, allowing the sax (now alto) to go somewhere approaching melody, the effect is heartbreaking. Often, however, the interplay between the two doesn’t seem to create an awful lot more than the sum of its parts.

Still, this is an eye-opening performance and a great contrast to usual indie attitudes towards musicianship.