If you were to ask the average opera-goer what their favourite opera by Johann Hasse is, the response would probably be a blank look. In many respects, Hasse is the Meyerbeer of the 18th century: hugely popular and respected in his lifetime, almost completely forgotten just a few decades afterwards, his fruitful artistic partnership with Metastasio today overlooked in favour of Gluck and Calzabigi, Mozart and Da Ponte. To hear the first British performance of his unrecorded Demetrio in modern times from Opera Settecento offered an intriguing chance to evaluate his work and consider the justice of his obscurity.

First impressions were good. The action takes place in Hellenistic Seleucia and is loosely inspired by the political turmoil surrounding the deposition of Demetrius I by Alexander Balus, a bit of a pip-squeak with a silver tongue and friends in Rome. Our eponymous hero is the son of the fallen king and, in Metastasio’s treatment, was rescued by Phenicius, brought up in a shepherd’s hut as Alceste and is eventually adopted by Phenicius, winning praise in battle under the Balus regime and the heart of Balus’ daughter, Cleonice, who after a revolt that ends in her father’s execution, is made Queen. As the work begins, Cleonice has to decide between her love for the ‘low-born’ Alceste, or Phenicius’ natural son, Olinto. And that’s largely it. Wavering, ranting, plotting and dreaming for nearly three hours, the opera has an almost claustrophobic intimacy to it which is brought to a sudden climax when the Cretans arrive on the doorstep bearing a posthumous communication from Demetrius I, confirming that his son’s name is Alceste. The implication is that everyone lives happily ever after – at least until Alceste himself was deposed and killed in the 120s BC. What’s striking is how easily Hasse is able to keep a fairly unadventurous plot musically stimulating over three hours, ably assisted by a libretto that has some sharply witty dialogue. There’s a degree of originality in the music that charms the ears; an aria for Cleonice in Act II with a heavy woodwind dynamic, while Olinto gets his own oboe obbligato in Act III.

Opera Settecento has been lucky enough to develop a strong relationship with the soprano Erica Eloff, well on her way to becoming the group’s resident diva. Eloff rarely fails to impress; here, storming onto the stage in the overture, she showed that typical vocal fire that indicates a total inhabitation of a role. If her voice was slightly underpowered in the lower register, it was more than compensated for by the security of her high notes, less sung and more fired. There was no dearth of subtlety though; Hasse’s rather lovely writing in Cleonice’s aria “Fra tanti pensieri” has a quivering, nervous fluctuation to distinguish between hope and fate that Eloff caught most sensitively.

She was well matched by Settecento newcomer, Ray Chenez, making a memorable debut as Olinto, seething and sniping his way through the opera. As tightly coiled as a spring, Chenez whipped out an unceasing cascade of rounded high notes through clenched jaw and with balled fists. His first aria “Di quell’ingiusto sdegno” showed off a crafted and elegant countertenor, with a clarity that makes it an engaging instrument. It helps that Hasse gives Olinto some characterful music – an innate thread of wrathful resentment runs through his arias, offering plenty of opportunities for bitter singing.

Another Settecento regular, Rupert Charlesworth, gave a strong performance as Phenicius, exhibiting his clean tenor with a lovely sense of line and natural phrasing. Unfogged at the top, he navigated the vocal leaps and bounds with daring flair, particularly enjoyable in “Disperato in mar tubato” which brought the second act to an exciting conclusion. As his adopted son and future king, Michael Taylor made varying impressions. In the first act, he was decidedly better in recitative where his swagger and keen sense of humorous delivery enlivened proceedings, but I didn’t personally take to his mannerisms in “Scherza il nocchier talora”, and his projection was somewhat lacking. He seemed to warm up in the second half with more simple delivery giving a stronger and more confident performance.

Ciara Hendrick’s small, but warm mezzo was sensitively deployed as Barsene, Cleonice’s handmaiden and rival for Alceste’s heart, always nuanced with an appreciation for the libretto and an enjoyably oaky bottom. Augusta Hebbert’s Mitrane was sweetly sung, with enough vocal and stage presence to make herself felt.

The Orchestra of Opera Settecento under the ever-energetic Leo Duarte played with fizz - plenty of grit in the strings and some enjoyable moments from the harpsichords, though there was awfully muggy playing from the horns in the second act. Overall, a work well worth hearing; a shame that there were so many empty seats.