Prom 45: Das Rheingold, Royal Albert Hall, London

Richard Strauss once flippantly advised young conductors to direct such blockbuster operas of his as Elektra "as if they were by Mendelssohn: fairy music".

Richard Strauss once flippantly advised young conductors to direct such blockbuster operas of his as Elektra "as if they were by Mendelssohn: fairy music". As the lissom strings of the Orchestra of the Age of Enlightenment rippled through the opening scene of Das Rheingold in this latest performance, it actually sounded as if it was Mendelssohn. But then, Wagner did pinch its main idea from the older composer's Fair Melusine overture.

This was the first instalment of Wagner's tetralogy Der Ring des Nibelungen to be unfolded over four successive Proms seasons with period instruments under Sir Simon Rattle. The advantages came over immediately: a different balance between grainy brass and volatile strings, and an overall lightness and transparency, with never a hint of Solti's brazen blasting or Karajan's treacly textures. Not least, this enabled Rattle to remind us that Das Rheingold retains much of the magic, pantomime, even comedy of early Romantic theatre, at least up to the peripeteia of Alberich's curse on the ring in the final scene, which has such dire consequences three music-dramas later.

Since more or less everything in Rattle's interpretation seemed to lead up to and away from this turning point, he was fortunate to have a superbly sonorous Alberich in the Kazakhstani baritone Oleg Bryjak, living every moment of the role. This Alberich might well have seemed to replace Sir Willard White's Wotan - noble-toned as ever, but rhythmically a little tentative for once - as protagonist of the whole drama, had he not been so wickedly countered at every turn by Kim Begley's equally vivid fire-god, Loge.

The other advantage of the period instruments was to let through so clearly the unforced voices of the strong cast, including a beautifully balanced trio of Rhine maidens from Kate Royal, Karen England and Christine Rice, an imperious yet vulnerable Fricka from Yvonne Naef and a well-contrasted pair of giants from Peter Rose and Robert Lloyd. And, as James Rutherford's Donner summoned the thunder clouds, it was nice to hear Wagner's relatively hushed orchestral dynamics respected for once, instead of the usual rampage.

But then, Sir Simon is a natural Wagnerian, pacing the paragraphs and placing the structural cadences with a seemingly effortless rightness. Most refreshing of all, his Rheingold reminded us that the methods Wagner was using here were newly devised, of bold originality, and only later to be elaborated into the longer-breathed subtleties of Tristan and Parsifal. There was a sense of proportion and balance restored about this reading that set at naught any momentary cavil one might have over the odd horn smudge or inexactitude of ensemble.

Booking: 020-7589 8212; www.bbc.co.uk/proms. Prom 45 available online to Thursday