"There is no such thing as a naked man," says shirtless frontman Simon Neil, as if quoting from some mysterious book of Biffy logic.
Oceansize's Mike Vennart is clearly chuffed to be playing second guitar tonight for Ayrshire's most famous musical trio, and Neil's words come in the midst of a promise to prise the incongruous pink estate-agent shirt from Vennart's back by the end of the evening. The context still doesn't explain Neil's slice of rock'n'roll wisdom. But it doesn't really matter what he says. This crowd are 30 minutes into a near flawless performance, and they're hanging on every word, note, and drumbeat.
Let's recap. After launching the set with the furious staccato melodies of "That Golden Rule" from their most recent album, Only Revolutions, Neil disappears down into the folds of the front row. After erupting back on stage to bait the crowd with a powerful "Living Is a Problem...", Biffy score a magnificent hatrick with a storming "Glitter and Trauma".
Biffy's last two clean-cut records may have put the band on the mainstream map, but in terms of songwriting, it's understandable why some feel the lads have lost their jagged bite – especially when newish track "Mountains" is juxtaposed with the thrashing drums, heavy bass, and screeching of the unrefined early classic "Bodies in Flight".
But things have clearly changed for Biffy, and it's written all over the band's performance. Once upon a showtime past, Neil would only rock to and fro and barely look at the crowd, hiding behind his long locks and beard. Now, lean, muscly torso outstretched, he's pelting across the stage whilst hammering strings like his life depends on it. It's this newfound self-assurance combined with the sheer quality of their live act that maintains Biffy's cult-hero status.
Biffy sign off with the gentle, acoustic "Machines" and the roaring crowd-pleaser "The Captain". Neil finishes up with a cool, "See you at Wembley". He undoubtedly will.