Without the Mozart brand label, his first full-length opera, Mitridate, Re di Ponto, would have remained in the oblivion into which it had fallen for the 200 years after its Milan premiere on Boxing Day 1770, when he was fourteen. Had he died of typhoid with his mother eight years later, the Sydney Festival would no more have imported a 1991 production from Covent Garden than that house would have revived any one of the other settings of this yarn of a jealous father (Mitradate), his Cain and Abel-like sons (Farnace and Sifare), and their high-minded girlfriends (Aspasia and Ismene).

That a teenager could achieve a triumph in the genre of opera seria proved how easy it was to follow the sagging formula. The number of arias per role was set. Interminable recitative clogged the action. Only once was there anything like a duet. Proof of Mozart’s genius as a stage composer came a decade later. The real surprise is that Mitridate can hold our attention, and for that benefaction we must thank the quality of the singers and the inspiration of the Covent Garden director Graham Vick and choreographer Ron Howell.

Vick sustained a single look on stage. Mobile blood red walls contrasted with primary-coloured costumes for the principals. Skirts fashioned from floral bedspreads was temporary lapse. Towards the close of Act III, one coup de theatre startled the less musical section of the audience back into wakefulness. Lighting cornered characters and shadows menaced them. Silences were as chilling as the thump of feet was suspense-filled from Howell’s Kabuki-style chorus. The Opera Australia team who have inflicted their vacant stages on us for a decade under the pretence of conveying Enlightenment values should take note of how an economy of means can elevate a multiplicity of effects.

The band that Mozart led from the keyboard in 1770 comprised 57 players, including 44 in the string section. Richard Tognetti waved his arms over the heads of 33 musicians from his Australian Chamber Orchestra, but only 21 strings. The consequence was that the passages of grandeur or terror lacked weight. This absence would have mattered less had he be given the rehearsals to achieve focus, shape or dynamics.

Having decided to proceed with the half the original forces, Tognetti bowed in the direction of the authentic performance by using replicas of eighteenth-century instruments. His description of them as “mongrel beasts” was dead accurate for the noises they emitted. The horn obbligato spoiled one of the finest vocal segments.

The singers overcame this lack of support to make the evening a constant entertainment, just as they ignored the rumble of the underground trains beneath the Capitol Theatre, one failing the Opera House pit cannot boast. As a bonus, they all looked their parts.

In the title role, tenor Donald Kaasch excelled at the dramatics of fury. His leaps into falsetto betrayed him.

To the part of his intended, Aspasia, Sonora Vaice contributed her rich but contained voice which, combined with her wraith-like appearance, made her extended elegaic contemplation of suicide so affecting that one wished that Gluck had reformed the opera a few years earlier so that she could have had a lament worthy of her expressiveness.

The good son, Sifare, was sung by a soprano, Sinead Mulhern, whose surety of delivery conveyed nobility of purpose from a voice which has more colour to offer than was required by his worthiness. The original performer said that if the public did not like his duet he would have himself castrated a second time. Saved from this fate by nature, Mulhern possesses the equipment to be no less certain of success.

As the malign son Farace, US counter-tenor Bejun Mehta proved crisp in diction and delicate in inflection if uncertain of projection. His alto timbre was lovely in the recitatives, but in the arias his stunning notes kept too greater a distance from each other. That disappointment was deepened by Mehta’s devilish accomplishments as an actor.

The low volumes of the singing were exposed once Australian soprano Emma Matthews began her first showstopper, before gracing even her highest notes. Matthews maintained her dramatic freshness more easily than her vocal bloom.

For his one aria, the Australian tenor John Heuzenroeder was happier singing words than embellishments.

The Sydney restaging and vocalists made Mitridate as appealing as it is ever going to be. Let’s hope that future festivals put their resources into acquainting us with more of the post-war operas that are musically and dramatically superior to this juvenili.