“We can’t do Aida here: it’s difficult to get the elephants,” Jeremy Gray apologises to his audience, explaining why Bampton Classical Opera’s 23rd summer production isn’t a familiar box-office classic, but is instead a rare small-scale work by Salieri. Not just rare: La grotta di Trofonio is one of nine Bampton adventures into opera’s forgotten archives which has probably resulted in a UK première (La grotta’s only other recorded London performance, in 1791, seems to have been a pasticcio, setting Casti’s libretto to music by a selection of other composers than Salieri). Sometimes, of course, obscurity is the kindest editor, but this brisk and vibrant comedy is a hidden masterpiece, combining the perils of courtship with the 18th century’s burgeoning taste for crackpot science.

Aristone has twin daughters, bookish Ofelia and fun-loving Dori. Each has found her ideal suitor: Ofelia shyly loves young philosopher Artemidoro, Dori is engaged to riotous Plistene. Aristone smiles on each match, and all seems perfect until the boys wander through the philosopher Trofonio’s cave in the woods – and emerge with their personalities swapped. The fiancées are distraught to find the philosopher dancing, the cad lost in dusty books: but soon it is the boys’ turn for disappointment, as they return to their former selves only to discover that Trofonio has now worked his magic on their girls... Cue much confusion, not least from an increasingly beleaguered Aristone, before a deeply satistfying quintet of reconciliation pronounces order, and love, is restored.

Reviving Salieri’s lost gem has become a personal passion for director and designer Jeremy Gray. His absolute commitment to the score, the work and this much-maligned composer shines out in Bampton’s engaging production, sung in exceptionally clear English by a talented cast. Casti’s original libretto has been deftly translated by Gilly French and Jeremy Gray, capturing much of the witty sensibility and rhythmic textures of 18th century Italian with its robustly patterned rhyme and piquant vocabulary. Staging is simple, but ambitious: we even have a revolve, and characters creatively use the garden in which we sit. Gray’s Edwardian setting, first a library, next a summer garden with bunting and lace tablecloths, recalls The Importance of Being Earnest, suiting Casti’s conflicting and quarrelsome love dynamics admirably, while Trofonio’s cave arrives in a brilliant modern incarnation which I won’t spoil for you: suffice it to say that you may be transported with delight. The Orchestra of Bampton Classical Opera, energetically conducted by Paul Wingfield, creates a luxurious sound, full of bright tension despite the evening breezes; even when a particularly bumptious zephyr decides to blow a section of scenery flat, professional execution stays serene.  

James Harrison is a warm-voiced and well-acted Aristone, showing a father’s bewildered concern for his daughters (and their hopeful spouses) as all the young people in his life seem to go mad, and enjoying every note of Salieri’s flowing “River” aria as he describes his wildly different daughters. Aoife O’Sullivan is charming as Dori, more than a slight air of Elizabeth Bennet in her merry dark eyes and witty retorts, her singing fresh, clear and appealing throughout and her mournful soliloquy despairing at Plistene’s change truly beautiful. Anna Starushkevych is lovely as Plato obsessive Ofelia, drawing a demure, uptight personality with plenty of inner intensity to exploit in her later transformation. Starushkevych’s creamy soprano exhibits great control, with wonderfully soft transitions between notes; her sometimes accented English remains articulate. The gentle sisterly rivalry, and their warm bond with their father, comes across well from both sopranos.

Christopher Turner makes an adorable Artemidoro, giving “These shady woods” wonderful ornamentation as he conveys the intense, innocent joy of a philosopher in nature. Artemidoro’s early awkwardness with Ofelia contrasts dramatically with his transformed personality, vibrantly at ease with the world and the universe, to the horror of all his friends. Naturally comic, with excellent timing and unflappable stagecraft, Nicholas Merryweather is delightful and clear-voiced as both versions of Plistene, whether the loudly-tweed-suited party boy or the withdrawn, Albert-Herring-like conformist in cardigan and tie. Matthew Stiff makes the lovable rogue philosopher Trofonio constantly compelling with his rich, dexterous bass. Stiff balances seriousness with quirky humour, giving us a man truly outside time and space.

In 1795, just a year before Mozart introduced Le nozze di Figaro to an unsuspecting (and, at first, unappreciative) world, Salieri produced La grotta di Trofonio for Emperor Joseph II and Vienna at large, receiving a rapturous international response: with 26 performances in its first run alone (Figaro received only nine!), within a decade Salieri’s romantic magical-buffo fairytale had been created in about 30 separate productions across Europe. Posterity may have reversed their positions, but Bampton Classical Opera’s joyful and melodious account of La grotta di Trofonio shows us Salieri can absolutely rival Mozart in wit, charm and creativity: and his music, brimming with hummable melodies, certainly sounds fabulous enough for any Emperor’s ear.