A million things happen during Devo’s gig tonight that just don’t happen at other Flow festival gigs. These include, but are not limited to: a mid-set pom-pom dance demonstration, lead singer Mark Mothersbaugh frisbeeing a series of the band’s trademark Energy Dome hats into the crowd, the playback of two long videos in which record company execs describe the band as failures, the band tearing themselves out of their yellow overalls only minutes after putting them on, and, three quarters of the way through, keyboardist Gerald Casale sidling up to a mic and booming, “GREETINGS, NORDIC SPUDS!”. They’ve even seemingly leant into this summer’s festival trend for retro football paraphernalia by getting in Carlo Ancelotti on guitar.

The thing is, although this stuff doesn’t happen at any other gig over the weekend, it clearly does happen at every Devo one, as the fifty or so ultras down the front prove: they’re all already rocking their own homemade Energy Domes long before Mothersbaugh’s handout, and they greet each unfolding act in this theatre of the absurd with a knowing fondness, clearly as delighted by its arch goofiness today as they were the first time they saw it. By the time the band are stripped down to shorts, t-shirts and knee pads for the show’s finale, I’ve no idea what’s happening, but the fact there is an elite handful 20 yards away who exactly do enforces the cult brilliance of the show: Devo’s hour on the main stage here offers a glimpse into a parallel world of ultimate, intimate, joyous fandom.

Almost as an aside, the music is also a revelation. Even if you don’t really know what Devo sound like, you sort of do: the post-punk synthpop art-rock they pioneered in the late 70s has, half a century on, become the indestructible lingua franca of independent guitar music, and they lean towards those foundational “hits” (UK Top 40 singles count: 0) here, with the likes of ‘Whip It’, ‘Mongoloid’, and ‘Uncontrollable Urge’ revealing the source of a winding river that has flowed in more recent years through Franz Ferdinand, Dry Cleaning, Squid and even Yard Act.

But to linger on the music too much is to miss the point (even if the riff to ‘Whip It’, still pinging around my brain the morning after, is testament to their brilliantly concise songwriting). What’s great about Devo is the obvious and unwavering dedication to their concept, aesthetic and delivery, that in turn inspires their ardent supporters so brilliantly and creates a rather enchanting mutual relationship between either side of the stage monitors. Like Sparks – another American band of the same vintage who feel far more European art clique than stadium-aiming unit shifters, and who inspire similar fan ardency – Devo’s essence lies in their delivery: revelling in the preposterous, and taking its brand of silliness brilliantly seriously.

Mark Mothersbaugh has called the current run of Devo shows their “farewell tour”. He’s also said there are plans for Devo to remain active for 50 more years. That contradiction feels very Devo: life-affirming, exuberant, and with no idea what will happen next.