Prom 44: Mahler Jugendorchester / Abbado, Royal Albert Hall, London

In youth is pleasure

Youth orchestras – and this time it was the turn of Claudio Abbado's Gustav Mahler Jugendorchester – come in greater numbers than their grown-up counterparts. The idea that they are growing into their sound is a nice one to hold on to. What you see – many doublings and a string section bigger than any even their namesake conceived – is not necessarily what you hear. The most striking feature of Abbado's orchestra is its lightness and transparency.

Only Bartok's Music for Strings, Percussion and Celesta seemed to stray farthest from its origins as a chamber piece – a double string orchestra, it's true, but one that is lean and argumentative. If the piece is, as some claim, a conscious reinvention of the Baroque concerto grosso, then the emphasis of this performance was on the "grosso". You couldn't see for strings. The percussion, relegated to one corner behind a bank of double basses, felt remote. No longer the solo group, no longer the driving force, the horse-power under the bonnet.

What I missed here – particularly, of course, in the two allegro movements – was a tight, wiry, quick-reflex sound. Even where these youngsters were fizzing with energy, the sheer weight of their numbers, the blizzard of tremolando effects, dissipated the effect. The performance was altogether bigger on atmosphere. The sound of many hushed voices at the outset – a furtive fugue if ever there was one, a fugue that almost dare not speak its name – was eerily disembodied like a remnant of past performances heard in this hall. Spooky, too, were the slow movement's slippery glissando effects. Very Stanley Kubrick.

Martha Argerich, the evening's soloist, has now turned up for three consecutive Prom seasons, which must be some kind of record for a lady whose reputation for cancellation must be up there with the late Michelangeli. But you can see that she's in her element here, doubly so when surrounded by young musicians and backed up by her friend Claudio Abbado with whom the rapport is telepathic. Their performance of Ravel's G major Piano Concerto was initially so relaxed, so casual, so effortless as to be almost horizontal.

But never be deceived by Argerich. What was truly remarkable about this reading and this playing was its illusory nature. The essence of the piece is jazz, and jazz is about furthering the threshold of improvisation and still coming home. Argerich probably plays this piece as much if not more than any other concerto in the repertoire and yet not one phrase could safely be predicted. Which is not to say that she strove to be unpredictable, just that she was unpredictable. A shift of emphasis here, a slightly different slant on a phrase there, a rhythm suddenly spiked to catch you unawares. She didn't wait for quiet from the audience before beginning her soft, museful vamp into the slow movement. We could listen if we liked. Whatever.

Abbado's youngsters – particularly his feisty wind soloists – clowned and caroused. Personality counted for far more than precision right down to some fashionably bright intonation. The great thing about these young players is their highly developed sense of characterisation. Debussy's La Mer was all about freedom, openness, and mobility, a lightness on the string, on the breath. As I say, they'll grow into their sound, but the spirit – typified by the exuberant climax of the central tableau which wind-surfed its way through the surf and spray – was unassailable.