So where are we? The initial setting, via looping video screens (all very Harry Potter) has the members of Elbow in baroque gold frames sitting in wing-backed chairs, against plush velvet, suggesting this is no night for raucous rock.
Much of the Bury men's evocative canon suggests a smoky jazz club, shirts open at the neck, a scotch in hand, lamenting lost loves.
But this is also The O2, many thousand strong, milling around looking to start their hearts with a jolt from 10-ton speakers.
But then the five guys (and their string quartet) head on to the stage, get The Birds out the way and there we are.
We're in Guy Garvey's front room. Or down his local. Such is his ease with his new-found celebrity, such is his comfort within his skin, such is his enjoyment at this relatively late flowering recognition that he exudes (and wryly suppresses) the sheer joy of it all.
Down there, portly, bearded, throwing one-liners at the crowd he resembles Ricky Gervais.
But then he starts to sing. He finds those notes from somewhere. He mixes the dry northern self-deprecation with operatic, heart-swelling vocals without a misstep and this gig drifts towards pure perfection on a sea of melody and musicality.
And the songs keep coming, tiny gems, neatly constructed, from the new album Build A Rocket Boys!, their breakthrough The Seldom Seen Kid and glories from further back.
The Bones Of You, Lippy Kids, Mirrorball, The Night Will Always Come, Loneliness Of A Tower Crane Driver.
He has a catwalk so he prowls while his colleagues, passive and involved in their work conjure an orchestra out of nothing.
At one point, it's just Guy and Craig Potter (also their producer) on an old battered joanna prickling eyes with the soulful Puncture Repair and fiendishly moving Some Riot.
Guy pours a cocktail for the five of them - Mark Potter, guitar; Craig Potter, keyboards; Pete Turner, bass; Richard Jupp, drums - to mark 20 years together. He makes one for us too.
We're new to the party, those of us who jumped on the bandwagon after the Mercury Prize, but he makes us all welcome, catches us up with the news, sings about times past.
But then we're back in business. We're pointing to the sky in Open Arms. Playing the role of choir in With Love, whooping tunelessly in Grounds For Divorce.
Forget being cool, Guy tells us, we're doing all the cheesy stuff tonight.
Then, when time has flown by it's One Day Like This. On your feet. Throw those curtains wide.
They saw that grown men left in tears after watching Toy Story 3. But Elbow's blend of magic and melancholy, nostalgia and bonhomie makes for better goosebump theatre.
It's true. One day like this a year would see me right.
