Just Jack, Islington Academy, London<img src="http://www.independent.co.uk/template/ver/gfx/threestar.gif"></img >

"I'm looking more emaciated than usual because I've been locked in my room for four days," said Jack Allsopp. "It feels good to be out." It was a good link into "Writer's Block", one of the north-London rapper's finer vignettes, dealing with being cooped up in a state of creative stagnation.

Allsopp was clearly delighted to be there - he bounced like Tigger and grinned beatifically for the whole of his 50-minute set. He'd waited a long time for this. But why call yourself Just Jack? Is it an allusion to Richmal Crompton's Just William series, or is the wiry rapper just full of himself?

His publicity machine, which has thrown its considerable weight behind the 31-year-old, would have you believe that Allsopp is an "off-kilter musical maverick". He's not. In fact, the pasty singer already enjoys the patronage of the "establishment" in the form of Elton John. But Just Jack has attracted some harsh press, with one music critic demanding that he go away in no uncertain terms. It seems that some are landing their sideswipes before Allsopp goes super-K T Tunstall-nova.

He's a likeable stage presence, and has a fabulous rapport with his four-piece band and his rapping partner, Hazel Sim. At their worst, they sound like a blend of slick early-Nineties jazz-funk acts such as Jamiroquai, Brand New Heavies or Galliano, but at their best, as on Allsopp's moodier material - "Disco Friends", for example - they're sumptuous.

We weren't treated to anything off Allsopp's 2003 debut album, The Outer Marker, which attracted mild praise and Elton's attentions but did little business. Most of the set concentrates on the latest, Overture, which will "do business" and is a far slicker affair. Allsopp has been compared to The Streets' Mike Skinner and to Lily Allen, but, in truth, he's softer than either. He even counts Luther Vandross as an influence, and has claimed that the late soul man's "R U Using Me" makes him "want to cry like a baby".

But, occasionally, his wry, playful lyrics really hit the mark, as on "Writer's Block: "I'm lovin' Mary Jane/Flyin' with Lois Lane/On board a bullet train."

After a silly encore just 38 minutes in, Allsopp returned and delivered what the young audience wanted: "Starz in their Eyes", his catchy hit mocking celebrity culture. It was a great success live, leaving Jack with a few more stars in his eyes. But how long can it last?

Just Jack plays Islington Academy, London, on Wednesday; UK tour begins 9 February