Sam Sparro, Camden Crawl, London<br/>Ipso factor, Camden Crawl, London

Existential Christian angst. This could be the Next Big Thing: The Camden Crawl, NW1's annual rock bazaar, seems to throw up bands on the cusp ... where fame beckons but it's pub gigs for now

There's always one. Every year at the Camden Crawl – the annual multi-band, multi-venue happening at which thousands of young folks charge up and down NW1's main thoroughfares in an attempt to catch as many acts as possible – there's somebody who's on the cusp. Somebody who, through a quirk of the time-lapse between being booked and actually performing, finds themselves playing a tiny boozer (as opposed to, say, the Electric Ballroom or Koko) when they're at the very apex of the breaking wave of stardom. Last year it was Calvin Harris who had the entire congregation of Crawl-goers trying to get into tranny cabaret pub The Black Cap. This year, playing the Earl of Camden (a nondescript pub), it's Sam Sparro who has them queuing around the block.

Sam Sparro is that classic template for an interesting pop star: the misfit who found his way into the mainstream. Too Australian for America, too American for Australia, and too openly gay for both, his peripatetic upbringing was, by all accounts, a solitary one. Suddenly, the United Kingdom has taken him to its heart, and his very-nearly-chart-topping single "Black and Gold" has correctly been hailed as this year's "Hey Ya!" or "Crazy", ie, a unifying soul-pop singalong that the whole world loves.

'Tis pity he's a Christian. It's always disappointing when you find that an artist you admire is an evolution-denier (although, if you're going to enforce it strictly, you'd have to set fire to the lion's share of your soul collection). But yes, he's one of them, and it was during a spell as a choirboy that funk diva Chaka Khan, who attended the same church, exclaimed, "Damn, that white boy can sing!"

Actually, it isn't a pity at all. Sparro's saving grace is that he's a doubter, and doubt is always more interesting than certainty. Far from being a strident saints-go-marching-in anthem, "Black and Gold" is the sound of confusion (unsurprising, given that Leviticus 20 would have him put to death merely for being what he is). This is what lends the song its delicious flavour of existential torment. It's a song that, in pondering the nature of existence ("Now I'm filled to the top with fear that it's all just a bunch of matter..."), seems to acknowledge Plath ("I talk to God, but the sky is empty"), if not quite Nietzsche ("God is dead"). Having been brought up to believe in an omniscient, omnipotent creator, the adult Sam (he's 23 now) confronts the possibility that there isn't one: the "you" in "If you're not really here/Then I don't wanna be, either...", one surmises, is the deity himself.

Not that the hordes are here to tackle theology. They're here to dance, and Sparro obliges. Walking through the crowd shrouded in a pale grey hoodie like a boxing champ in waiting and sporting the sort of specs with white plastic frames that Trevor Horn used to wear in The Buggles, it isn't long before the former is dark with sweat and the latter are discarded.

Sparro proves he's not a one-hit wonder ("Sick" recalls the shoulder-pad soul of Vandross and O'Neal, "21st Century Life" the unapologetic uncoolness of Kool & The Gang, "Cottonmouth" the louche gyrations of Imagination) and more than a one-trick pony (he can do a mean falsetto, and his skinny white frame is home to a phat voice, like gargling a chocolate milkshake). It feels like the whole of Camden is here, teetering on every available ledge to get a view (I can only see his reflection by positioning myself at an angle to a handily placed mirror). Everyone's wearing their affirmative funk face. When the bouncers allow one-out, one-in, there's literally a conga line through the door.

What Sparro may lack in energy he vampirically sucks from his audience. By the time he's knockin' em cold with "Black and Gold", he's given up contemplating the divine, and goes crawlabout.

Sparro is preceded by Ipso Facto, a decidedly icier prospect. Ipso Facto have been hailed, or dismissed (depending on your viewpoint), as a "female Horrors", largely for social reasons (they're old friends from Southend), and perhaps for their shared aesthetic (vintage and monochrome), but sonically they have little in common with the garage-goth abandon of their male counterparts.

Rosalie Cunningham, Cherish Kaya, Victoria Smith and Samantha Valentine wear immaculate 1960s dresses, elegant geometric bobs, and even their eyebrows are sculpted to precision. Their music echoes this scrupulous attention to detail. These aren't songs so much as exercises, or – let's be really pretentious about this – études.

This is the art of disciplined repression. Ipso Facto's minimal baroque is typified by "Smoke and Mirrors", a waltz around an empty ballroom haunted by Rosalie's voice (which is itself stalked by the ghosts of Siouxsie Sioux and Julie Driscoll). Ipso Facto will never be massive. But they will be a lot of people's favourite un-massive band.