The New Pornographers, Koko<br/>Ida Maria, Notting Hill Arts Club, London

Northern lights shine in London

Arcade Fire announced Canada's pop renaissance to the world this year, but Vancouver's New Pornographers helped begin it a full decade back. One of the loosely affiliated pop communes that their country specialises in (Broken Social Scene and the ultimate underground collective, Godspeed You! Black Emperor, share the model), their most famous member, the alt-country siren Neko Case, rarely appears with them now. Chief Pornographer, A C Newman's niece Kathryn Calder, fills Case's role when not with her own band Immaculate Machine, one of five groups the band members moonlight in.

This has all somehow coalesced, on the fourth New Pornographers album, Challengers, into a cohesive master class in subtly politicised power pop. The album has the tunes to make them stars, though you wonder if they'd want it.

Most of Canada's expat community seems to be at the bar, at least until the band kick straight in with the fine new single "Mutiny, I Promise You". Written by another absent but crucial Pornographer, Danny Bejar, it has the familiarity and surprise of a classic hit. Played as a sophisticated take on a glam-rock stomp, the red-bearded Newman attacks its lyrics of louche urban hedonism.

Keyboardist Calder is mostly his wryly amused foil. But when she sings lead herself, it's with the character and confidence of someone with her own band. When they harmonise or, as during "All the Old Showstoppers", the band stop and start on a dime, it is the sound of high pop craft. When the venue's old-fashioned glitterball starts to spin, it seems only right.

The band briefly live up to their name when some of the crowd catch the references to mutual oral sex in "The Spirit of Giving". It's harder to hear Bejar's declaration that he's "sick of America and her screaming decay". Calder's slowly squeezed accordion makes more impact, and during Newman's "My Rights Versus Yours", the crystallisation of pop's potential for private change in the lines "the truth in one free afternoon" nonetheless remains part of the tune's swaggering uplift. Other bands, such as The Shins, add academic intellect to basic pop forms; The New Pornographers also reverse the process, reducing the intellectuals and would-be outsiders in the crowd to dancing fools.

Over in Notting Hill, meanwhile, is a 23-year-old from the north of Norway who is known even in that ex-Viking country for wild behaviour. A cracked rib and a bloody face from head-butting a guitar are among the injuries sustained by Ida Maria at previous shows. When your hero is Iggy Pop, these are badges of honour. But self-harm has happily yet to become a shtick, and tonight's half-hour club set, the start of her Sony-backed UK assault, is notable for controlled aggression.

Maria at first only hints at how damaged bones could result from this music. "Morning Light" is introduced as about being "double-drunk"; her voice is a sandpaper growl as it channels regret pounding her head in the morning. "Louie", "about exactly the same thing," is the best expression of her band's garage-band power pop. One moment they sound like The Libertines at their jauntiest, the next they're tackling prog-rock scales.

"Stella", which seemed sure to form the hat trick of booze odes, is instead about giving God's powers to a 23-year-old prostitute from New York. By its end, Maria's seems about to break down and cry. For "Better When You're Naked", she invites mutual disrobing, and ends flat on the floor. And this is just a prelude to "Oh My God", her first UK single, "the soundtrack to a panic attack". By now, her mascara is running, her hair is a mess, and her movements have become clumsy, like a child unsure of its body. Shoving into her guitarist like a nuisance drunk, she is no longer glamorous. Slowly moving her pointing finger over the crowd like a zombie Supreme, she sings, "You think I'm in control," as she tries to drive herself out of it.

She doesn't offer real danger by threatening or implicating the crowd, as Iggy used to. And when she rolls on to her front as if dead, it's as fake as James Brown's old routine. But when a dropped guitar accidentally bounces on her head, the act becomes real enough. Maria isn't as unhinged as she'd like. But there is genuine fascination in her attempt at self-transformation.