‘Lager, lager, lager!’Not the usual refrain you’d normally hear chanted by a 2500-strong audience at the Royal Festival Hall on the south bank. But that was the state of affairs last night as techno duo Underworld celebrated the 20th anniversary of their Junior Boy’s Own records debut LP dubnobasswithmyheadman.

Their set closing Born Slippy.NUXX may have launched their career stratospheric back in 1996 when it saw out filmmaker – long time fan of Karl Hyde and Rick Smith –  Danny Boyle’s Trainspotting. But it was dubnobaswithmyheadman two years earlier that had set their career on the track they would follow for the ensuring 20 years and five albums.

A fusing of electronica, rock instrumentation, beats and pounding techno, with Hyde’s hypnotic, spoken word-esque vocal delivery, it was a landmark album for them (it set Hyde and Smith on their future  direction) but also for the genre, confounding expectations, rewriting the rules, resetting parameters. Getting the 20-years-down-the-track-treatment, it still sounds vital, virile and damn irresistible as it got a full run out last night (in LP running order).

Opening with the woozy Dark and Long, the Royal Festival Hall, normally the setting for more serene theatrical stage shows and performances, became a full on tech-fest. Young and old – those that were there the first time round, looking on with smiles of chemical remembrance, as well as those who have discovered Underworld through their younger years musical journeys of discovery – refused to sit from the opening beats to the climactic, euphoric strobe-addled moments. It was a set of celebration, triumphalism and above all fun – Hyde beamed from ear-to-ear throughout, sharing knowing glances with Smith that said ‘this is pretty fucking special’. And it was.

Second song Mmm Skyscraper I Love You was a near 15 minute epic of dirty, sexy throbbing techno that built and swooped, and Cowgirl a roof-raising anthem complete with Hyde’s trademark jilts and jolts dancing. After ending the ‘first act’ with LP closer M.E., it was down to the business of an hour-long encore.

First up was Rez; often paired with Cowgirl in the reverse order in the live setting, here it got a stand-alone moment of its own. “This was one he wrote in his bedroom,”Hyde explains by way of introduction, disappearing stage right to sit atop a table as his compatriot took the limelight, one of many such circumstances over the course of the show.

Running through the likes of Minneapolis and Bigmouth, with Hyde taking to the harmonica in one of many live instrumentation moments, the set closer was a foregone conclusion. But when this predetermination is one of the finest slices of dancefloor delirium to have ever been conceived, this is no bad thing. Born Slippy .NUXX came storming out of the gates and absolutely laid waste to the crowd, Hyde’s half-chanting, half-ranting, surreal snapshot lyrics winding their way over one of the best techno tunes ever.

“We’ve been away for a while,” Hyde nonchalantly quipped at one point. Their music has longevity that is only achieved through creativity that has attained classic status. This was a one off, for the moment, but there are more live dates booked for the Spring – you’d be a fool to miss out. Relive dub… or experience it for the first time, whatever, just experience it!!