We’ve now reached a point where it’s near impossible to tell the difference between a mixtape and an album. The price tag attached to it used to be the biggest difference but now with streaming, you’re basically making albums available to your fans for free. Still, as Charli XCX discovered, if you call it a “mixtape” over an “album” your label is more likely to let the public have it faster without all the roadblocks that push back albums.

With that in mind, despite it being called a mixtape, Number 1 Angel is an album. In fact, it’s Charli’s best album to date. It picks up on her debut True Romance‘s dark electronic vibes but injects what she’s learnt about top line writing and collaborating to make it a far more mature and invigorating listen. It’s also the latest chapter in her relationship with PC Music, one that started with her SOPHIE-produced EP Vroom Vroom. This record has been predominantly produced by PC Music head A.G. Cook and together they compliment eachother expertly. Cook pushes the instrumental as far towards the experimental as possible while Charli ushers them gently into the pop world. It’s this balance that makes Number 1 Angel so successful.

While her previous single After The Afterparty was a glossy, sugar high, this mixtape is much darker. In a way, it’s the aftermath – the point where the afterparty has ended and the loneliness and regret creeps in. On opener Dreamer she’s still in party mode, the tempo is slowing but she’s got her crew, Starrah and RAYE. It’s a pop song but it puts an emphasis on the verses in the same way a rap song does and the three of them lock together effortlessly.

It’s after this that things take a turn. She recruits MØ for 3AM (Pull Up), a frustrating track about a late night relationship going around in circles. It’s a perky, glassy backdrop but Charli’s vocals darken the tone as she delivers one of the most emotional verses of the record. MØ’s contribution is just as perfect as the two trade in that same brand of shouty, raw pop. Charli’s collaborations on this record have been chosen so carefully and she bonds with each of them. When she sings, “Go fuck yourself, don’t say you’re sorry,” in the final chorus it feels as if she’s being supported by MØ in the background.

If that song made it to radio, it would sound slightly weird but it would gain traction. She’s aiming her songs at the pop world but she’s not going to conform for a quick pop hit (something she’s slightly guilty of with Boom Clap. Several moments on this record make a strong argument for what pop is going to sound like next. Roll With me takes us straight back to ’90s commercial rave music and would likely revolutionise acceptable tempos on the radio while Emotional reinvents the big Sia ballad with far more interesting textures and sounds.

There are other moments where she takes the crisp, clean pop format and messes with it so much that it falls into the experimental world. ILY2‘s verses are conventional but the chorus distorts and shreds adding an extra grit to the track. It then ends on a howling guitar solo. It’s these unexpected parts that make the mixtape so thrilling.

One of the main criticisms of PC Music is that it sometimes sounds so synthetic that it’s hard to connect to or attach human qualities to. This mixtape is otherworldly but Charli is so direct and personal with her lyrics that she adds the human that Cook’s productions are often bereft of. “We had something that never happened,” she sings on Emotional, exploring the grittiest imperfections in her voice in the same way Rihanna did with so much success on ANTI. “Baby, you’re the love of my life,” she sings on Drugs, piling on the hyperbole but really believing in her own melodrama. Throughout she captures all the frustrations of love in real time from the feeling that you can’t survive without it (Drugs) to the anger when someone screws you over (Blame It On You).

She brightens up for the mixtape’s closing parts pulling Uffie out of hiding for the highlight Babygirl. She brings ’80s Californian vibes and dreamlike verses that are just incomprehensibly genius. She’s soft and flirty, juxtaposing Uffie’s harsh, attitude-filled verse. Together, they’ve created what may be the feel-good pop song of the year. She leaves us with the circling rave synths of Lipgloss, handing the verses to CupkKake and proving that pop/hip-hop crossovers don’t always have to be so cut and dried.

It’s likely that Charli’s left the radio jams for her forthcoming album but that doesn’t mean this tape is any less delectable. She’s always been a great pop writer but on Sucker it was as if she felt pressure to make things a little more normal as to not scare commercial audiences. Number 1 Angel proves she’s found a way to deliver the hooks and stay weird and wild. She wrote and recorded this over a matter of weeks in LA and the pace she works at means that we’re served up her emotions in real time. She might hate what she’s said here in months to come but it’s so exciting to have an ‘of the moment’ popstar who just wants to set free what she’s working on to move onto the next thing. Number 1 Angel feels restless, energetic and frustrated. That’s the best part about it.