In all the build up to Billie Eilish’s Glastonbury headline set, all the talk about the youngest ever solo headliner, the meteoric rise, the rare genuinely working sibling writing partnership, everyone seemed to lose sight of some important facts: mainly that here we are, the biggest moment of the biggest festival in the UK and Billie roars on stage with a song about killing yourself, madness, and what death is like. The glorious morbidity of Billie Eilish’s career is not being hidden here. She’s not glossed up or gone mainstream, even as the coverage has got glossy and mainstream.

We had wondered how the indisputable modern queen of bedroom headphone introspection would get on in front of a hundred thousand people in a field (I don’t know how big the crowd is, it’s dark and famously that makes things hard), but we needn’t had worried: Billie comes with some brilliant production that can be turned up loud to make it sound like we’re all heading through a vortex into one of Dr Strange’s darker dimensions, and Billie’s absolutely up for playing the grinning demonic middlewoman.

A few songs in, I’m thrilled, because it turns out these songs sound very good extremely loud in the open air as well as cranked in a small room, but we’re actively afraid for the British viewing public at home who’ve turned into see the current pop wunderkind with her blonde snazzy album cover only to find a satanic priestess giving it everything.

Earlier today I said in a review Wet Leg didn’t seem fazed by Glastonbury. No one expected Billie to be, given her recent few years, this is far from the top of her achievement list. I said Phoebe Bridgers was smoothly professional. But Billie is something else, it’s like the Billie we see in interviews off stage is just an awkward pause between this, the thing she does and enjoys better than anything, the voice of something dark finally able to come out. It’s like Billie gets on stage and gets to unwrap and flex her blackened wings.

Which reading back a few minutes after I wrote it sounds pretty weird, but that’s the vibe we’ve got here, no trace of artifice. It’s authentically dark, and I suspect every Billie fan here is connecting to that the same way. She’s not above stopping to ask different bits of the crowd to react, and what a cheer they give her, although it has to be said the back of the crowd sounded sadder than the ones at the front. I assume those up close have been here since 9am so fair enough. Then we’re given the three rules of a Billie show and in a glimpse of humanity she does seem, briefly, taken aback by the size and keenness of this all. We’re then treated to something akin to a therapy session where we’re told to loosen up, have a tantrum to release, scream and clear our minds. If I had another half an hour and a thousand words I’d muse at length about how this nexus of pure evil music cathartic and modern psychological therapy, but you’re lucky I don’t. Could have done without the fucking huge spider imagery however.

The show continues, with Billie nailing her seemingly endless bag supply of vibes, acting like a DC universe villain who’d grown up on the Cure and Bauhaus. Just when the songs start to thin, when the catalogue isn’t quite big enough yet, Billie goes back to playing with the crowd, ordering them about like a pro and it gets crazy again before a total left turn: Billie and Phineas cracking out the acoustic guitars for a dual singalong. A short while later we get Happier Than Ever, the first song that doesn’t sound like art and instead sounds worryingly like a direct line into the real mind of the young woman and her life offstage. It still makes us worried for her, even as it’s some of the truest words about us all you’ll hear. But don’t worry, she’s soon back to grinning like a possessor.

It feels like things are winding down when Billie tells us to hug each other, and dedicates the song to Phineas, but in the back of our minds we know Bad Guy hasn’t happened yet… but when it does everyone sings along. We close on Happier than Ever. Which we aren’t, because the show is over.

The real world is out there. But not in here. For one plus glorious hour we got to connect with the HD, 3D full sensory version of Billie Eilish’s cathartic, understanding derangement, and it was glorious.