Opera / AIDA London Philharmonic, Royal Festival Hall, London

For those who still believe that the best, the only, great stagings of Verdi's Aida happen in the imagination, Monday's concert performance with the London Philharmonic will have provided spectacle enough for the most extravagant tastes. Whether or not Zubin Mehta represented a substantial saving over the cast of thousands is a moot point. That he was excellent value is not. It takes a Mehta to remind us just how much of Aida's scenic beauty and drama is written into the score - and how rarely it comes off the page.

How often, in the still of a darkened theatre, we've held our breath in fearful anticipation of those muted violins of the Prelude: so horribly exposed, so vulnerable. Yet here, in the unforgiving brightness and formality of the concert hall, they immediately cast a spell: as one, pure voice, perfectly in tune, the ethereal spirit of Aida abroad. You closed your eyes and she was there, silhouetted on the banks of the Nile. The London Philharmonic respond to Mehta. It's that fluid and commanding technique: it instils confidence,flamboyance, the will to dare. The dramatic impulses in the score went off like electric charges, a trenchant string figure here, a brassy sforzando or the crack of timpani there. The confrontation between Aida and Amonasro in the Nile Scene boiled over in a tremendous wave of yapping brass and whiplash strings as the full horror of her father's demands finally dawned. Then there was the Judgement Scene, trombones bearing down on their lowest register, the accuser's finger pointed towards the tombs. And the sweep of the Triumph Scene, with Mehta in his element, tracing out the big choral invocations, urging his sopranos ever upwards to their climactic peaks. Why, he even enlivened the ballet music.

The title role was sung by Leona Mitchell, a real Aida voice, but one which I suspect has seen better days. It's a big, beautiful sound, easily dominating the ensembles. And no one could doubt the sincerity, the commitment behind it. But the complete Aida is the possessor of a seamless legato, a natural ability to float long phrases on the breath, no accents, no untoward bulges. Mitchell had real problems on that score. She was nowhere near equal to that marvellous moment in the Triumph Scene when the great ensemble momentarily subsides, leaving Aida to spin a brief but glorious cadenza. And an Aida who cannot sing the difficult ascent to the high C of "O patria mia", as one phrase in one breath, should look to her laurels. Still, "Verona" acting apart, she had her moments.

Dennis O'Neill, her Radames, has done a whole lot better. Even so, it was more than creditable, with some lovely mezza voce work in the final scene. You have to admire a tenor who tries for the finer nuances. Not that you win plaudits for trying. One had to sympathise with his valiant attempt to set up the final diminuendo of "Celeste Aida" (how many even attempt it?) only for it to misfire. A cruel business, singing.

As is so often the case with this opera, Amneris all but stole the show. Florence Quivar was simply terrific. Here was an Amneris whose musical intelligence and dramatic engagement made one realise how often big ladies with pneumatic chest voices win easy applause from easy options.

But it was Mehta's evening. To see him attending to his singers, reading their rubatos, nursing their insecurities - that in itself was an object lesson that some practitioners in the field might do well to heed.

n Second performance: 6.30pm tomorrow RFH, SBC (0171-960 4242)