Today, the Midlands, tomorrow, the world

There aren't many fields in which it's a compliment to say that someone could be mistaken for an American, but alongside rodeo-riding and burger preparation, the field of R'n'B is one of them. Set Shola Ama and Eternal next to the edgy modernism of Destiny's Child, Missy Elliot, Melky Sedeck and Kelis and the local contenders seem as if they have as much purpose and direction as an eight-year-old waiting in M&S for her mum to finish the shopping. So far, the British invasion has only one big gun in its arsenal: Jamelia.

There aren't many fields in which it's a compliment to say that someone could be mistaken for an American, but alongside rodeo-riding and burger preparation, the field of R'n'B is one of them. Set Shola Ama and Eternal next to the edgy modernism of Destiny's Child, Missy Elliot, Melky Sedeck and Kelis and the local contenders seem as if they have as much purpose and direction as an eight-year-old waiting in M&S for her mum to finish the shopping. So far, the British invasion has only one big gun in its arsenal: Jamelia.

Listen to the 19-year-old's debut album, Drama, and you'd guess her home town was Birmingham, Alabama before you guessed Birmingham, England. From the sassy relationship lyrics to the spiky orchestral snippets to the complicated ticks and spurts of the rhythm track, Drama is an album of honed contemporary pop. The fact that Jamelia Niela Davis co-writes all her songs, as well as providing the requisite piercing warble, suggests that she is not just the lucky beneficiary of other people's talents, either. The only question is whether she can perform in concert as well as she performs on record.

On Tuesday, Jamelia got her first ever headlining show off to a promising start: she arrived on stage half-an-hour late. Inconsiderate as that might seem, it's the done thing in the strange world of hip-hop and r'n'b, where it's deemed a faux pas to turn up during the same month as the one printed on the ticket. Besides, Jamelia had the excuse that she had, quite possibly, spent the extra half-hour in make-up and wardrobe. Her hair was a sculptural masterpiece, a tattoo made of glitter dripped down one arm and there was a whole window's worth of cut-glass jewels studding her wristband and vest.

Her musicians must have spent as long getting ready as she did. Jamelia could have easily got away with using backing tapes, but instead she was accompanied by a five-piece band and three singers, all in matching outfits, and with a rich but tightly focused sound. If the Hanover Grand's small stage weren't full enough already, she was also joined by a guest duettist on "Guilty" and, for a few songs, two open-shirted dancers who pointed their abdominal muscles at the ladies in the house.

For lavish preparation, then, Jamelia gave the Americans a run for their money. But the real revelation was that she had the natural stage presence to match it. With the physique of Naomi Campbell's younger sister, she looked radiant (I say that in a wholly objective, journalistic sort of way), and when she slipped into the dance routines she proved herself an effortlessly slinky mover. Also, considering how confident a performer she was, it was gratifying to note that she was still a human being, gulping back shy laughter between songs.

Jamelia is already Britain's brightest r'n'b starlet, and if Tuesday's form holds there's no reason why she shouldn't be spoken of in international terms. My only cavil would be with the concept of one song, "Room 101". Orwell's chamber of horrors has already been travestied as a comedy talkshow; now Jamelia wants us to think of it as a love nest: a "little hideaway that nobody knows". What's that got to do with having rats shoved in your face by a Fascist torturer?

The Union Chapel may have been deconsecrated, but its gothic arches and shadows can still echo with music that's as profoundly spiritual as any requiem. It's the perfect venue for Sigur Rós. With an overpowering sound that isn't done justice by comparisons to Mogwai, Labradford, Spiritualized and the Cocteau Twins, the young Icelandic quartet has made one of this year's essential albums. There are only a few homes in Iceland, apparently, that don't have a copy of ÿgætis Byrjun, and over here the band's swelling tides of emotion are making waves so big that in the Union Chapel on Thursday there were people climbing over the pews to get a better view.

Sigur Rós soon restored the serene and reverent atmosphere envisaged by the architects. First a string quartet set the mood, then the band built up melodies that were stratospheric and ethereal but had a precision and structure more usually associated with classical music. No one in the group says anything, and beyond what's needed to play the instruments, the only movement on stage comes from the candles that flicker at the back. Kjartan Sveinsson appears to be nodding off at the keyboard as he picks out funereal organ parts; Orri Páll Dyrason favours soft beaters and brushes for his drumming; Georg Holm strums chords on his bass; and Jón Birgisson strokes the strings of his guitar with a violin bow.

When he lifted the instrument up to his face, those of a nervous disposition in the audience must have thought: Oh my God, he's going to play a solo with his teeth. Instead, the Tintin-quiffed, barefoot frontman sang directly into his guitar pick-ups, and his angelic keening became a far away, eerie lament. His lyrics are a mixture of Icelandic and "Hopelandic", his own invented language, and while it's possible that he's secretly chuckling to himself, because he's actually reciting a bus timetable, this mystery only deepens to the otherworldly ambience. The surroundings help, of course, but I suspect that even in a Burger King, Sigur Rós would sound sublime.