N-Dubz, Shepherd's Bush Empire, London

Fiercely slick teenage kicks

Who'd have guessed that three youngsters, straight out of north-west London, would make the remarkable ascent to pop royalty with music that plays on the travails of the 21st-century teenager? In the case of the Mobo Award-winning N-Dubz, this involves songs about everything from getting girls knocked up and unfaithful boyfriends to smoking weed and dodging the cops. The late Byron Contostavlos, Dappy's father and former Mungo Jerry member, was instrumental in managing the earlier incarnation of the group first made famous on the then-named Channel U. Since then and after many years of honing their sound and soap-opera, slang-ridden narratives, Dappy, his cousin Tulisa and Fazer have secured a chart-topping formula that tonight leaves the crowd screaming with unbridled, teary-eyed delirium.

It's a fascinating spectacle, especially as there are just as many men proclaiming their loyalties to the grime-cum-pop band. "I remember when we were broke and we never had a pot to piss in! You changed our lives!" screams the effusive Dappy, following a lively introduction of "Strong Again". The second surprise is that with the backing of a band, their catchy musical offerings sound phenomenal, if not credible, and there's rarely a moment when the audience isn't singing along, word-for-word. Having said that, there's something a little wrong with under-11s nodding along to the bubbling "Sex". It's a good thing, then, that moments earlier, the group have warned of the dangers of teenage pregnancy with "Shoulda Put Something On", inspiring some audience members to toss condoms on to the stage. "Listen to the words!" warns Dappy.

N-Dubz borrow much of their showmanship from seasoned American R&B and hip-hop stars, keeping the affair snappy, interactive and fiercely professional – there are at least three outfit changes, jet bursts of dry ice, and during one interval, an advertisement for their current album, Against All Odds, just in case the crowd might have opted to download it illegally instead. Tulisa is a strong vocalist, playing up to her street diva status thanks to a few well-placed wind machines. She adds weight to Fazer and Dappy's sprightly delivery as the beacon of girl power, with "Ouch" dedicated to "the twat in your life", and a neck-roll thrown in for added effect. The fellas, on the other hand, are awkward sex symbols. Bare-chested and nearly drowning in a sea of their fans when they jump off stage, they prove that, when it comes to teen love, there's no accounting for taste.

Cameos come in the shapes of Chipmunk on "Defeat You", and a very likeable Mr Hudson, who joins forces with the crew on their latest single "Playing with Fire". Mass pandemonium ensues, and to keep up the hysteria, you almost wish that Tinchy Stryder had also trotted in to assist them on their chart-topper "Number One". Not that they needed the help, judging by the reaction of the sobbing fan who joined them on stage as they performed an intense rendition of "Papa Can You Hear Me?". Add to that "I Need You" as the finale, and it's hard to not be impressed by N-Dubz's superstardom.