What is the difference between the National Youth Orchestra and a full-time professional ensemble? Very little, other than that the pros are likely to possess more expensive instruments. Yet even that distinction has become blurred by the NYO's summer programme, for which the orchestra's original leader, John Ludlow, has lent an old fiddle to the present incumbent, 18-year-old Roberto Ruisi.

An old fiddle made by Stradivarius, that is.

Ruisi seemed supremely unperturbed by having over a million pound's-worth of spruce and maple tucked beneath his chin; but then it is a hallmark of the NYO that it is up for anything, even the ill-co-ordinated puppet at the heart of Stravinsky's ballet Petrushka, whose dissonant signature chord was delivered with the brash confidence of strings getting into a tangle on purpose.

Prokofiev's skittish First Piano Concerto was given a fast and furious performance by Louis Schwizgebel, who negotiated the work's bravura back-flip by shaping the introductory theme like a triumphant conclusion and rounding off with an introductory flourish. But it was an apt choice, as Prokofiev's youthful showpiece was written while still at the Moscow Conservatory, where his habit of compiling statistics of his fellow students' mistakes provoked them to jump on him, throw him to the floor and pull his ears. Nothing like that goes on at the NYO's residential workshops, I'm sure.

In later life, Witold Lutoslawski distanced himself from his early, folk-inspired Concerto for Orchestra, claiming: "I wrote as I was able since I could not yet write as I wished." Yet it was a perfect showcase for the strength and depth of this remarkable ensemble. Though conducting the NYO for the first time, Edward Gardner seemed to have developed an instant rapport, igniting individual sections throughout the mysterious nocturne like fireflies.

• Programme repeated at Symphony Hall Birmingham, 9 August. Box office: 0121-780 4949. BBC Proms Royal Albert Hall London 10 August (0207-589 821).