Michael Rother, Hans-Joachim Roedelius and Dieter Mobius took to the stage for the very first time in the UK to open this year’s Ether ragbag on the South Bank. Shuffling on to stand behind their desks, this looked more like the opening night for a symposium of retired German scientists; actually that is probably unfair on the spritely Rother, who is still a few years away from collecting his autobus pass. In front of footage of themselves as far younger men, and facing an extremely diverse and expectant crowd, they began to tinker with their boxes of wires. And, slightly worryingly, a laptop.

Almost instantly, the mood in the room was deflated. The first couple of numbers drifted along in a fog of vapid ambience, not helped by the quietest sound I have heard at a concert in some time. You could hear the crowd over the music; I felt like I was in the Crucible in the Sheffield watching the snooker (”such a knowledgeable crowd”, thanks JV), but whereas that atmosphere known as “the cough that clicks”, this was “the cough that pulses gently”. There was not a lot to listen to, and not a lot to see; after half an hour of vague, metallic sounds and barely discernable rhythm, Harmonia were in danger of their reputation evaporating into the ether.

A screamed “MAKE IT LOUDER!” got the message across. Rother switched to guitar, although they chose, oddly, to submerge it under a disco beat. Things were getting slightly better, but with the addition of that slightly embarrassing feeling you would get watching your dad dance to Snoop Dogg. Those ghostly images of the threesome on the screen behind were hanging in the air with the pungency of Belgian fertiliser. You couldn’t ignore it; this just wasn’t living up to past glories.

After an interlude of what sounded like bird song and planes buzzing overhead, they began to pull it back. Into some shimmering pulses they dropped the bomb: the motorik beat. Clearly a sample of live drums, the spirit of the late Klaus Dinger took centre stage. Via this quintessential rhythm, and some fuzzily euphoric guitar from Rother, they hauled the crowd back into the performance. At this louder volume, even the ambient sections that followed managed (which included, amusingly, some sampled coughing - was that us?) to avoid lapsing into tedium. They switched back to more crowd-pleasing motorik (an electronic version this time, better), and some buzzy looped guitar, and half the crowd - not me, I still wasn’t convinced they had earned it on the night - rose to their feet to acclaim them.

After a stunning encore of a vocal-free version of “Deluxe” from their 1975 album of the same name, I was won over. Rother by this time was running space-rock-amok amongst some pounding beats, grinning like a teenager. Closing my eyes, for a brief moment I visualised a young, long-haired German group creating something new and exciting.