Charli XCX. Sebright Arms, London The Joy Formidable, The Lexington, London

Is this electro-pop's newest star? Or just Christina Aguilera for hipsters?

Charlie XCX pumps pugnacious electropop (Getty Images)

Hackney Road in east London is border country. The first thing I see, stepping out of Cambridge Heath station, is some cooler-than-thou chimpanzee riding on a Segway, but there's something seedy going on behind the optimistically located Radisson Edwardian.

It's an area that's still on the turn, and one backstreet basement is a foothold of the gentrifying incomers. The Sebright Arms is a former old man's pub – worn-out red carpets still in place – that's become a young buck's den, and its sweaty cellar is playing host to an artist who's also living on a frontier: the fractious but fruitful line between underground cool and mainstream pop.

I'd always wondered what happened to the underage singer from Nathan Barley ("Bad to have a bad uncle …"), but maybe she grew up into Charli XCX. With her crop top, panda eyes and big hair, XCX is what you'd get if a Bratz doll suddenly came to life, like Kim Cattrall in Mannequin. The former Slade School of Art student, real name Charlotte Aitchison, is still only 20, but has been knocking around since 2008 when she was still a Hertfordshire schoolgirl. In between, she co-founded feminist fanzine Shut Your Pretty Mouth, and spent this summer supporting Coldplay and Santigold and played at Azealia Banks's mermaid ball.

XCX deals in pugnacious electro-pop, all repetitive choruses, emphatic thwacks of the drum pad and the sort of crystalline synth arpeggios which mean that, when the fire alarm goes off, no one panics because they assume it's part of the show. Clearly inspired by the likes of Peaches, Uffie and Robyn (indeed, Charli's forthcoming album features the skills of Robyn producer, and former Liverpool midfielder, Patrik Berger), she's somewhere on most tipsters' next-most-likely-to lists. If only because the last crop of British electro-dames (La Roux, Little Boots) has gone quiet and there's a window of opportunity for a Christina Aguilera for hipsters.

"Nuclear Seasons", with its big Ladytron chords, is undeniably a big tune, but the stripper-goth cover of Echo and the Bunnymen's "The Killing Moon" is superfluous, and the posh-girl way she says "shit" and punches the air is not entirely convincing, like being mugged by someone from Made in Chelsea.

Maybe she'll step up and be the one to set the city alight this autumn. But for now, London is keeping its powder dry.

For all the cerise sequins and feathered fairy lights, The Joy Formidable are a determinedly glamourless band.

They're clearly good people, and good company. When singer-guitarist Ritzy Bryan expresses disgust at the sweat patch on the floor under bassist Rhydian, he replies: "At least one of us is working hard." She, with practised timing, comes back with "Two words: four strings", and drummer Matt Thomas gives it the comedy kaboom.

And they're a solid, decent indie rock band, who are hard to dislike. But harder to adore. Maybe it's just the temperature in this airless room in sweltering late summer, but for all the crowdsurfing from the faithful down the front, what's missing is a crackle of excitement. The most excited whoop comes when Rhydian belts an upright drum with a big lollipop drumstick and Ritzy joins in. To be fair, in this humidity, the Second Coming of Christ would be greeted with indifference.

You find yourself wishing they had given their songwriting the same kind of welly. The proof will be in their second album, Wolf Law, recorded in a log cabin in Portland, Maine. On the evidence of tonight's excerpts, the pastoral surroundings affected their sound somewhat, but they can still kick up a big bad noise with appealing relish.

"I was talking to squirrels and possums," says Bryan of the sessions. "I was fuckin' Snow White by the end of it." Now there's a video treatment that wouldn't make it off the drawing board.

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