La Calisto, Hampstead Garden Opera

Baroque operas are like buses. You wait years for some Cavalli to come along, and then three of his operas arrive almost at once. It all started with English Touring Opera’s Jason last October – a witty and endlessly shape-shifting work – followed by the Royal Opera’s glossy L’Ormindo at the Globe’s Sam Wanamaker Playhouse last month. Now, undeterred by larger rivals, Hampstead Garden Opera continue the trend with La Calisto.

HGO are a fixture of London’s fringe opera scene, staging considered, well-funded productions with strong young singers in the theatre above Highgate’s Gatehouse pub. This latest is no exception, and if the vocal performances are more variable than sometimes this can be explained by the unusual challenges of Cavalli’s music. Rather than the formal recitative and aria divides of later opera seria, the composer’s music exists in a fluid space that drifts freely between recitative and arioso, rarely settling anywhere long or giving its singers a chance to settle into sustained musical set-pieces.

Diana and her band of virgin huntresses roam over scrap-heaps and deserts in combats, Hunger Games-style

Slashing the original score down to a brisk two hours, Joe Austin’s elegant production transplants the action to a post-apocalyptic landscape. Diana and her band of virgin huntresses roam over scrap-heaps and deserts in combats, Hunger Games-style, struggling for survival, while the Gods (apparently styled by Liza Minnelli) descend to meddle and seduce. It’s all a natural, plausible extrapolation of the original until the English libretto gets involved.

The composite product of Anne Ridler and Austin’s own translation, its awkward, Anglo-Saxon architecture batters the ear with infelicities. This arisoso writing is unforgiving to anything but the smooth curves of Italian, but would have been better served by a more neutral translation than this effortfully current and colloquial approach. Once you get over that, however, there’s much to enjoy.

The cast is dominated by Philippa Boyle’s ferocious Juno (pictured right). Here’s a woman you really wouldn’t want to wrong – all sequins and scheming vengeance, and in possession of some of the finest coloratura of the evening. Boyle took charge of Cavalli’s lines, playing with them texturally just as she toyed deliciously with Teresa Pells’ Calisto. Her wayward Jove (Peter Brooke) was a worthy consort, balancing schoolboy silliness with his spivvish henchman Mercury (Tom Dupernex) with some decidedly manly singing – finding a sustained melodic line through even the more fragmented moments of this music.

Strong support comes from James Hall’s Endymion – surely this is a young countertenor we’re going to hear a lot more from – and his beloved Diana, the poised Felicity Turner. Special mention must also be made of Madeleine Sexton, as the oversexed “goat-boy” Satirino, whose grubby knees and gangling awkwardness are the perfect echo of her forthright vocal delivery, and made me long to see her Cherubino. Vocally miscast in the central role, soprano Teresa Pells (pictured left) struggled to contain her large instrument within the role’s fidgety, nimble contours. Tuning and precision both suffered, and she gave us power where we wanted delicacy and beauty - particularly frustrating when her acting was so good.

Directed from the harpsichord by Oliver-John Ruthven, the band – Musica Poetica London – are a delight. Theorbo, recorders, harp and violins enrich the continuo core of cello and harpsichord, anchoring us firmly in the 17^th century, and offering enough authenticity to chafe fruitfully against Austin’s stylized contemporary direction. So if you missed Jason or couldn’t get tickets to L’Ormindo, you could do a lot worse than explore Cavalli up in Highgate.

• La Calisto is at Upstairs at the Gatehouse until 4 May