A double bill of rare operas: it’s like Christmas has come early in London. The Guildhall School of Music and Drama are pairing Debussy’s sober, profound retelling of the Prodigal Son (apparently one of only a few of his own works which his father liked, and special to him always, despite being written for an exam) with Donizetti’s sparkling court comedy Francesca di Foix (rescued from obscurity by those Indiana Jones-esque explorers of opera archives, Opera Rara). Wildly different and each superb, the duo makes for a moving and riotously funny evening, perfect for anyone whose approach to opera has got a bit stale (or a beginner who thinks opera might be dull: they will be swiftly and dramatically convinced otherwise!).

Strictly, L’enfant prodigue is not an opera at all: it’s a cantata. But it has been often performed as a one-act opera: and as such, works extremely well, even though the action is fairly static. The arc of the story is short: the Mother’s recognition, the Son’s repentance, the Father’s eventual rapturous welcome into the bosom of the broken family. Yannis Thavoris’ minimalist set, with a dramatic silhouetted opening sequence lit by David Howe, illustrates the story without dominating it, and manages somehow to be both classically timeless and faintly French at the same time. Debussy’s music is deliriously beautiful and dreamy: in contrast to the alien, ethereal sounds he used for his only full opera (Pelléas et Mélisande), L’enfant prodigue is full of such rich, warm tones that it made me think irresistibly of Disney for grown-ups in its simpler moments. But it’s more complex than that, with moments of drama nicely highlighted by sharp, rattlesnake sounds, and real emotional anguish in the singing. The Guildhall Orchestra, conducted by Dominic Wheeler, brought us all the rapture of Debussy’s music: and the main soloists, Lauren Fagan (Lia, the mother), Joseph Padfield (Siméon, the father) and Gérard Schneider (Azaël, the prodigal son) all conveyed despair, hope, repentance and joy with moving musicality. It’s all quite sombre and serious; and, at the end, almost suspiciously redemptive.

And this makes our subsequent plunge into Donizetti all the more exhilarating. Here, Yannis Thavoris’ design is not just beautiful: it is visionary. Truly, one of the most exciting sets I have seen for a while, and he must be applauded. We find ourselves “hunting” in an achingly cool Parisian fashion house – Valois, revealing their collection for “PRINTEMPS-ETE 1525”. Anyone who has rifled (or fantasised about rifling) the coathangers at a major-label sample sale will adore this cleverly observed set. Not only is the pursuit of haute couture a perfect modern simile for the medieval courtly hunting party; the orgiastic devotion of all to the magnificent King makes sense when he is a cult fashion designer, here incarnated as Karl Lagerfeld (one fan hilariously falls to the floor in a faint whenever he appears, and all gasp when he removes his sunglasses for what can only be described as a “Blue Steel” moment). Away from the hunt, we remove to the Court: which is, obviously, Wimbledon, sponsored by Valois, complete with Frow and tennis-playing soldiers, with sweat bands over their halberds, doing synchronised dance routines on Centre Court (including an obligatory “jazz racquets” finish, choreographed brilliantly by Victoria Newlyn) which had the entire audience incoherent with laughter from start to finish.

The Guildhall Orchestra played with what can only be described as infectious enthusiasm: the joyous mood they created spread through the whole auditorium, as this delicious opera became more and more charming with each passing phrase. Piran Legg (the King) effortlessly filled the space with his voice, making every line seem utterly natural; his voice just got better as the opera went on. Legg is definitely one to watch. Anna Gillingham (our eponymous heroine) sang so exquisitely in her opening scene that I actually gasped; her performance had astonishingly promising moments, and her acting is already assured and effective. Her first entrance, in full burqa, sparkled with just-got-out-of-jail glee. Szymon Wach was a brilliantly hand-wringing, desperately jealous Count, and Joshua Owen Mills an urbane and confident Duke. The whole company did Donizetti proud – and proved the value of the work of Opera Rara in rescuing a gem like this from perpetual obscurity.

Though I’m grateful for their choice, quite why the Guildhall chose to put these two particular operas together is a question I still can’t answer. They’re so very, very different. But their differences – stylistic, musical, philosophical – do at least provide an extraordinarily broad platform on which to showcase the skills of the stars of the future currently developing their talents at the Guildhall. It is the chance to see singers like Legg and Gillingham at an early stage of their career that makes any trip here exciting: Bryn Terfel’s name glitters in gold from a prize board in the entrance hall. Who knows who might be up there next?