Jamie Cullum, Royal Concert Hall, Glasgow

How strange to be Jamie Cullum. A year ago, the 24-year-old singer-pianist was still playing the Pizza Express Jazz Club in Soho for his bread and butter. Now he's sitting on a double-platinum album, Twentysomething (his third, the first fruit of last summer's £1m signing to Universal), reportedly outselling Robbie and Kylie, and setting off on a sellout UK tour fresh from duetting with Katie Melua at last week's Brits, where he'd been nominated in the Best British Breakthrough category. Despite the seemingly meteoric ascent and regardless of Cullum's baby-faced appearance, the kid has paid his dues- on cruise ships, around the Continental café/bar circuit and on the English provincial jazz scene.

One key element in Cullum's appeal, which has seen him hailed as a new jazz/crossover star to rival Norah Jones, was immediately apparent from the moment he gambolled on stage. Jazz isn't renowned as the most light-hearted of genres, but this boy was unmistakably out for some fun, diving into a spicily angular yet loose-limbed version of "Lucky So-and-So", complete with his trademark tricks of hand-drumming on the piano strings and case, before jumping on to the stool and stamping on the keys. Having followed up with the wry strut'n'stroll of Twentysomething's title track, it was time for a first brisk promenade around the auditorium, before divesting himself of jacket, tie and shirt, leaving only the T-shirt, jeans and Converse sneakers he favours.

Besides his effervescent personality and performance style, it's the way that Cullum's uncontrived eagerness and evident enjoyment feed into his music that explains his rapid success, combining as they do with a thorough understanding of vintage jazz idioms and the great American songbook. While he may attract extra attention with his covers of Radiohead and Jimi Hendrix - a non-standard repertoire he expanded here with boldly assured reworkings of the Who's "My Generation" and Pharrell Williams's "Frontin'" - it was his interpretation of such classics as "I Get a Kick out of You" and "Old Devil Moon" that really proved his mettle.

The arrangements throughout the show involved different permutations of his six-strong backing line-up, from the intimacy of a trio to the splash of the full band. Mixing in strains of funk, soul, blues, hip hop and jump-jive, Cullum's colleagues, meanwhile, vied with his quicksilver piano work in an array of sizzling short solos. Cullum's original songwriting, too, extends his range still further towards the quality end of the pop market, as with the gentle "All at Sea", its folky lyricism building to a force- fully urgent climax, and a new, country-tinged reverie in praise of idleness, "Why Do Today What You Could Do Tomorrow?".