Tinie Tempah/Plan B, Roundhouse, London

"We made it to the point where UK music is the hottest thing right now!" screams Tinie Tempah, the 21-year-old London rapper who, in the last four months, has made a rapid rise to pop supremacy, not least thanks to his frolicking hits "Frisky" and "Pass Out". Both were proof that for all of urban music's false starts, Tempah and his comrades (Dizzee Rascal, Chipmunk, Tinchy Stryder) could finally boast of developing a profile big enough to sit in the mainstream and allow them to perform at cool shows like tonight's latest gig in the iTunes festival series.

Unsurprisingly, "Pass Out" earns the wildest cheers of the night, wrapping up a crowd-pleasing performance that sees the energetic rapper whisk through new and old songs, each delivered with the charm of Tempah's flashy persona.

But fellow rapper-turned-crooner Plan B struggles with the bravado when he takes his turn 30 minutes later. You'd imagine that having a number-one selling album, The Defamation of Strickland Banks, and a couple of Top 10 singles would have the 26-year-old so convinced of his own hype, he should have been flying around the Roundhouse on a harness with a Superman cape, not avoiding eye-contact with the crowd and pacing the stage awkwardly, like his suit trousers were two sizes too small.

To his credit, he's a phenomenal singer and one who most likely did a "Susan Boyle" when record executives gave him the once-over. His best moments are during the finger-clicking "She Said" and a riotous cover of Paolo Nutini's "Coming Up Easy", and with the help of beatboxer Faith SFX, he does an even meaner remix of Seal's "Kiss from a Rose". It's at this point that he makes up for his subdued start with an energetic jostle to the end, wrapping up with the romping "Stay Too Long" and proving that he and Tinie Tempah truly deserve their fame – even if it's been a long time coming.