Alt-J lead the celebrations at London's O2 Arena

Tonight is all about celebrations. There’s the fact that Blaenavon are playing to one of the biggest crowds they’ve ever played to. There's the fact that alt-J are returning to an arena they once capped off their last run in, but now are stepping into as they unveil their fresh new and invigorating era. And there’s the fact that The O2 itself is marking 10 years of defining arena shows and snapchat memories that thousands still replay day in day out. Across it all, there’s something undeniably unique about the evening that lays itself out. alt-J are a band you would never of put a bet on when it comes to headlining the vast stage they now stand proud on, never mind their position as one of (if not the) mainstream-infiltrating escapists of 2017 - yet their return to The O2 stage is nothing short of a confirmation. Confirmation of a band in 10 years time we’ll be writing about as the floodgate to the exciting and enthralling scene we’ll see in front of our eyes. That feat, is echoed in every moment at The O2 tonight. It’s echoed through every move Blaenavon make as they step onto the arena field. We’ve seen them deliver a gripping modern-day masterpiece with debut album ‘Take Care’ and tonight is nothing short of a staggering confirmation of how big this band could truly become. Unfazed by the occasion, they rip through a set of dazzling heights as if they’re playing the landmark shows they’ve already tucked under their belt - full of confidence, knowing nods and an unfiltered commitment to leaving it all on the stage. ‘Orthodox Man’ reverbs with an immediate urgency, ‘My Bark Is Your Bite’ cuts into the masses gathered and ‘I Will Be The World’ unravels with an insatiable urgency that stuns the thousands gathered into one overflowing mass of devotion. Frontman Ben Gregory leads the procession, in a set that would convert anyone who’d stumble onto the show they’d witness in front of them - with every twitch, motion and figure entirely rich in depth and style. The O2 is a huge stage, and Blaenavon make that stage look like any other night in their faultless schedule - and as ‘Prague 99’ closes out their set, one statement is clear. Blaenavon will be back to soundtrack those universal moments, and no matter what the stage - it’ll soon be made theirs. alt-J should never have been here. When experimental beats and sounds emanated from the Uni dorms they gathered around, The O2 must of seem like a ridiculous daydream that would never fit the flicks and motions they wanted to explore. Yet, it says it all that they’ve returned not only with a new album, but with the confidence of a band leading the way in forward-thinking creative hooks. With album number three, alt-J can boast the pedigree of an outfit that have soundtracked a generation of lovers, thinkers and dreamers - and at The O2 their full power is blistered on display in emphatic fashion. With a jaw-dropping light show in tow, their spell reaches every corner of the arena in front of them right from the chilling opening pulls of ‘3WW’, and it continues through a set that simply doesn’t sit still. Daring, bold and brave, it’s a set that picks through three albums that constantly look to reinvention. ‘Left Hand Free’ elicits hand in the air devotion, ‘In Cold Blood’ already pulses like a favourite you’ve known for years, ’Taro’ shimmers just as bright as it did the first time you locked your ears around it and ‘Matilda’ triggers a choir of voices to emerge across the stalls and standing gathered. It’s a catalogue that can jump between time and album, and always sound so undeniably fresh and exciting. Above it all, alt-J look comfortable in the position they now find themselves, a band embracing their standing whilst remaining fearless in the paths they lead down. “Fuck you, I’ll do what I want to do” echoes out of frontman Joe Newman’s mouth during ‘Hit Me With The Snare’. On tonight’s evidence, doing what they want to do is exactly what makes Alt-J so special. An experience that no other band could deliver. Now that’s worth celebrating.