The Philosopher's Stone, Bampton Classical Opera, Bampton

Tweeting swallows, passing ducks, an unscripted chanticleer – pure music-hall, you might think – resolutely failed to faze Bampton Classical Opera's British- premiere production of The Philosopher's Stone. Credited to "Mozart and others" (Mozart supplied the catty bits), and dating from a year before The Magic Flute, The Philosopher's Stone, strong on chorus though thinner on ensembles, enjoyed a similar Viennese popularity. Its plot, by Schikaneder, is less high-minded but comparably zany, and Barry Millington's tongue-in-cheek translation – apt, funny and sensitive to the vocal line – enters slap-bang into the spirit of the original.

So, too, does Jeremy Gray's production. Gray, who both directs (with Gillian Pitt) and designs, has built up both a composite team and his own intelligent directorial style, informed by a wry sense of humour. You never know what trompe l'oeil will impinge next: outrageous colours, Escher-esque structures, bizarre trappings. Gray can pull off importing a silver bird, a spaceman, a Dalek, neo-Copernican paraphernalia (the subtitle could have been Die Silberinsel), because he sustains each visual leitmotif (Lubano has a silver bottle; even the villain is a silver-black villain).

The scarlet-orange-yellow garb of the ubiquitous space-worshipping chorus gets recycled as a fringe to each principal's costume, in the heavenward trajectory of votive balloons, and in the lighting coup at the close of Act I that signposts the static, brassy, ghoulish male chorus of Act II, "Astromonte dies" (shades of Trinculo-Caliban). Nothing – even the make-up – feels haphazard: everything fits.

At last, Bampton has resolved its musical side. The woodwind (richly counterpointed for Astromonte's entry) is better than ever; the horn obbligati, top- notch; the Bennelong Ensemble strings vigorous, if less punchy than a period band – although the violas (for Nadir) gave a good imitation.

I found myself grass-tapping to Alexander Briger's Mozartian pacings: the spirited hunting vignette (the chorus, including male and female quartets, was terrific); Lubano's strophic "To trust a girl would not be wise" (more glorious translation jingles); and surpassing all, the fabulously paced Act II overture, and prolonged Act I finale. The true hero was Mozart's colleague, the 21-year-old newly fledged theatre composer Johann Henneberg, soon to be conductor of The Magic Flute, who delivered the lion's share of the music: a stunning talent.

The cast did well, with reservations: the odd exit prompted unnecessary musical pauses. Neither Sadik (Nicholas Merryweather) nor the central Sarastro figure, Astromonte (Ben Hulett), whose space-suited arrival climaxes Act I, calculated their moves (or identities) adequately.

Gillian Keith's well-sung Lubanara over-egged the feline. Nadir (Mark Wilde) is a tenor of real calibre ("Can I be dreaming?" is pure Tamino), but slightly fudged – like Hulett's Astromonte – his fearsome Queen of the Night-style coloratura.

Amanda Pitt, ever-restrained, made an appealing Nadine. Mark Saberton, a wide-ranging baritone of marked potential in the Pizarro-Scarpia mould, made a strong if pantomimically villainous Eutifronte. The Devil doesn't get the best tunes; Rachel Bickerton's Genie had some of them.

None seemed much of an actor-improviser apart from Thomas Guthrie, whose janitor-Lubano, laced with quirky gesture and sidling nuance, produced convincingly good singing in aria and duet alike.