JAZZ DIARY / Destruction, invention and creation: Phil Johnson reports on wondrous hands at the annual Brecon Jazz Festival

It is 9.30pm on Saturday night, and the town square in Brecon is heaving with people; some of the people are heaving too. A torrential rainstorm is in progress and a large group of young men has stripped down to the waist to dance to the thrum of a second-line rhythm from somewhere off in the distance. A youth has climbed to the top of the Duke of Wellington's statue and is having difficulty getting down. It is only when the young men start bouncing beer bellies against each other, that the police decide to move in.

The atmosphere - like some of the haircuts - was medieval. Mostly, the aggression was as ritualised as crowd behaviour at a football match, but by the end of the night 48 people had been arrested, for drunkenness, criminal damage, assaults against the police and drug offences. It has little to do with jazz but in Brecon, which for the rest of the year is basically Sheepsville, the annual Jazz Festival has become institutionalised locally as a Feast of Misrule.

Down the road at the huge Market Hall, Courtney Pine was coming to the end of a vigorously crowd-pleasing set. Making his Brecon debut in what programmer Jed Williams described as 'the Kenny Ball slot' - the traditional Saturday night good-time music event - Pine was gloriously up to the mark. With Bheki Mseleku on piano and a good, functional band, he succeeded in blending fine playing with a populist approach, attracting people who probably know him as much from his tour with the Pet Shop Boys as his jazz work. The etiquette of jazz is so confusing that someone passed a note up to Pine to ask if it was OK to dance. He nodded and went into a version of Bob Marley's 'Natural Mystic', where it is difficult not to.

Most of the other Brecon concert venues are small and cloistered and attract the already converted. At the little theatre of Christ College, the pianist Jay McShann - Charlie Parker's first major employer - created an almost universal glow of well-being just by being there. He produced sharp music, easing through a repertoire of standards and blues with wily charm, stroking the keys with essence of Kansas City swing.

On the same piano on the opening Friday night, Michel Petrucciani hit the keys rather harder. Someone once described a boogie-woogie pianist as having a left hand like God. Petrucciani is blessed with two divine hands but the right is particularly wondrous. While most piano players play in phrases, timing their runs to a sequence of breaks and bar-rests, Petrucciani's right hand doesn't stop, reeling out a line of invention that just goes on and on. The extravagant opening applause may have been partly a sympathy vote - Petrucciani has 'glass bones', stands only three feet tall and walks to the piano with the aid of crutches - but the closing ovation was a tribute to genius.

The pianist Dick Hyman - who appeared at the Guildhall on Saturday afternoon - doesn't so much play a tune as perform an autopsy on it, the song spread- eagled on the slab of the keyboard before him. An author of famous fake-books of substitute chords to jazz standards and a composer of soundtracks for Woody Allen, Hyman comes on like a character from an Allen film. He sat down at the keyboard and pulled from his pocket a list of songs that he said he would play through. Starting with 'Thou Swell' and 'Ain't Misbehavin' ', he took each number through a sequence of jazz piano styles before starting the history lesson proper, from Joplin rags to James P Johnson stride. Halfway though, he started asking for requests. It was an offer not to be refused; the best cocktail-jazz pianist played 'Someone To Watch Over Me' and a piece from 'The Purple Rose of Cairo' and it was wonderful.

The conventional line on 22- year-old Texas trumpeter Roy Hargrove and his equally young saxophonist Antonio Hart goes: 'Sure they can play but don't they really need to age and suffer a bit before they have something to say?' Looking defiantly young and happy, the quintet performed probably the most exciting set of straightahead jazz I've ever heard. With the possibly even younger Marc Cary on piano, Rodney Whitaker on bass and Gregory Hutchinson on drums, Hargrove and Hart dispelled any doubts about the worth of retro-jazz. Unlike many older leaders, Hargrove listens to his band too. After soloing, he moves out of the spotlight but doesn't slink away, staying around to encourage and applaud.

The Paris-based American saxophonist Johnny Griffin, by contrast, slopes off backstage whenever possible. This led to one of the festival's most comic moments when, in the second of two back-to-back concerts, Griffin opened at breakneck speed on what he described afterwards as a 'destruction' of Cole Porter's 'Just One Of Those Things'.

The drummer Charles 'Lolo' Bellonzi looked tired before they had even started. When Griffin signalled for him to solo Bellonzi didn't look grateful; when the leader walked offstage and left him to it, he seemed in some distress. At length Griffin reappeared and Bellonzi must have sensed relief, only to be thrown into a hurtling series of four-bar breaks with the band, requiring him to solo again. Even at the song's close - after a good 20 minutes - Griffin made Bellonzi suffer, forcing him into a prolonged coda. At the final beat the drummer shrugged meaningfully and just had time to take his jacket off before they were off again.

For many festival-goers the highlight of the three days was the two Sunday Market Hall concerts by guitarist Pat Metheny in a trio with bassist Dave Holland and drummer Roy Haynes. Holland sounded magnificent and Haynes was equally impressive, but to my mind Metheny doesn't connect emotionally. He is technically brilliant, - a beautiful version of Jobim's 'Insensatez' showed subtlety as well as power - but something about his whining guitar sound, either straight or synth-assisted, lacks weight. Perhaps he needs to suffer too, though I doubt it.