AX / Dudamel / Philharmonia Orchestra, Royal Festival Hall, London

When a dynamic young musician suddenly emerges from the unlikeliest background and amid sensational publicity, standing ovations are liable to follow, whatever the quality of the actual performances.

Yet the 27-year-old Venezuelan Gustavo Dudamel is manifestly the real thing. Conducting without score, he not only remembers and signals every cue of a complex orchestral piece, but feels and shapes every phrase and paragraph with natural musicality and life. His gestures may be extravagant, but they are unfailingly functional – and evidently infectious. Rarely has one seen the Philharmonia Orchestra responding – indeed throwing itself about – with such un-English physicality.

Clearly, they were all having a terrific time. That was in Mahler's perfervid hour-long Symphony No 5 in C sharp minor (1902), which comprised the main part of their Royal Festival Hall bill. But preceding it with one of Mozart's calmest piano concertos also showed Dudamel's range. From the insinuating little violin phrase that launches the first movement, his reading of the Piano Concerto No 17 in G, K453 (1784), had an exceptional spaciousness and translucence, with the limpid arabesques of Emanuel Ax's piano invoking radiant responses from the woodwind principals of the Philharmonia. There were moments of poise in the slow movement when time almost seemed to stand still, yet the accelerating variations of the finale had all their due vivacity.

Not much calm in the Mahler, which sets out in funereal marchings interspersed with outbursts of hysterical grief, centres on a huge Alpine knees-up of a scherzo full of echoing horns; and resolves, by way of an intensely hushed love song for strings and harp – the famous Adagietto of Death in Venice notoriety – in a joyous finale, unalloyed for once by Mahlerian irony, in which bucolic tunes turn all manner of contrapuntal cartwheels, and even stand on their heads.

And it was all here in this sur- passingly vivid reading. Maybe there were a few moments when the hysteria lost focus; maybe the Adagietto was a little too lovingly nuanced quite to carry through. But in general the choice of tempi and the pointing of detail were convincingly balanced, while the emotional and sonorous intensity were tremendous.