Clouds of cannabis infused smoke billow from the crowd, glowing blue and purple as they ascend and loiter amongst the light rigging. Pure white beams shatter and disperse, smashing against rotating disco balls and patterning the walls with a whirlwind of bubbled light.

Onstage; a silhouette highlighted with an orange glow. Poised delicately, one hand glued firmly to a horsehair bow, the other grasps the neck of a guitar. This moment has been a long time coming, and as Sigur Ros frontman, Jon Thor Birgisson, furiously grates his bow across the strings, I can’t help but shudder with excitement.

It’s a borderline spiritual feeling as the room heaves with a roaring gale of sound and moody emotion. Almost as if a stormy wind is blowing fresh upon my face, the music is entrancing and deep but somehow also refreshing and energising. Over the rumbles of bowed guitar and silken bass, cylindrical piano parts and gentle, punctuating drumbeats lays that haunting voice, completing everything so beautifully Sigur Ros. Motivational, optimistic and yet utterly foreign, Icelandic dolphin sounds manipulate my mind and emotions. Swinging from ecstatic grins to choking back tears. I, along with everyone else in the audience stare, eyes gripped on four young men so passion soaked and absorbed in their music, I begin to wonder if they even know we’re still here.

After a short hour-and-a-half set, the music climaxes and instruments are carefully abandoned to an applause that lasts for what seems like an age. Sigur Ros, accompanied by an apparently exhausted and exhilarated female string quartet, return to the stage for the last time this evening, not for an encore; not to play their most famous pop hit or to whip up the most violent mosh they possibly can; but to join hands and to bow, as any classical musician would…