One of the odd gifts of reviewing opera regularly is that you are sometimes exposed to violently clashing influences within the space of a few days. On Friday, I was enveloped in the passionate intensity of Fulham Opera’s bleak, immersive Der fliegende Holländer; on Tuesday, I found myself at New Sussex Opera’s community production of Ambroise Thomas’s unrepentantly twee romance Mignon. It was rather like tucking into the finest Chateaubriand steak, before turning to a shelf-stale vanilla cupcake laced with inch-thick pink icing. Usually, I relish this: it’s good mental discipline to engage with such different things in close succession. But, with Mignon, the contrast was so profound as to actually make enjoying the work difficult.

This is not to say we didn’t get some good singing. We were treated to two exceptional voices in Victoria Simmonds (Mignon) and Ruth Jenkins-Róbertsson (Philine), with a warm tenor Laertes from Christopher Diffey, and a generally capable Lothario from baritone Adrian Powter, a little underpowered at the end of his phrases but blessed with lovely tone. We also had an enthusiastic orchestra in the St Paul’s Sinfonia, conducted with great energy by Nicholas Jenkins through the wafting sweeps of Thomas’ score, which sounds exactly as you would expect. The exception is Philine’s extraordinary, dazzling Titania aria, which blazes like a Roman candle of originality in the otherwise beige fog of multipurpose music-that-sounds -Romantic-and-French. Fun scenery from designer Eleanor Wdowski consisted mainly of a series of differently sized trunks, some large enough to act as doors and others small enough to be tables, with judicious use of tablecloths and dust sheets to disguise them into other things when required. It was all nicely done; I felt just inexpressibly bored, as cardboard scene morphed into cardboard scene, the paper-thin plot wilting away in front of me as the hours stretched ahead.

New Sussex Opera’s Oberon last year was a triumph, incorporating a keen amateur chorus with professional singers to heartwarming effect. This year, enthusiasm still reigns on stage, but the gap between chorus and principals has grown larger. Timing in the choruses, particularly, went wildly astray, the NSO Chorus often pulling away from Nicholas Jenkins’ proffered rhythm like startled animals, an operation of sheer musical survival rather than style. Acting, generally, didn’t match last year’s standard either; the Chorus looked the part in their sumptuous period 1920s costumes, but didn’t seem relaxed on stage, while the principals either tended to over-act (Jenkins-Róbertsson in unrepentant diva mode) or under-act: Ted Schmitz’s wimpy Wilhelm was so vague a stage presence, it was a wonder any women were interested in him at all. Victoria Simmonds alone acted Mignon with recognisable intensity and restraint, but Mignon herself is a hard character to make really loveable or interesting: there’s just not enough there in the libretto, even for Simmonds.

It seems Ambroise Thomas didn’t like Wagner, or have any sympathy for his reform agenda, whether musical or dramatic. As the night went on, my gratitude to Wagner, to his aims and achievements for opera as a whole, and to his impact on everyone who came after him, only deepened. Thomas gives us an opera which somehow manages to be both entirely predictable in its plot, yet completely unjustified by the bare semblance of characterisation which he grudges to his principals. Mignon is a cipher; Wilhelm is a cipher; they are all ciphers, and the scenario in which they find themselves is almost devoid of emotional authenticity, or human interest, as a result.

Despite plenty of good ideas from director Harry Fehr, we still had some singers lapsing into “park and bark”, swallowing vowels while singing, and other bad old habits which have no place on a contemporary opera stage. Fehr’s finest moment was undoubtedly Titania's aria, delivered with bravura energy by Jenkins-Róbertsson with well-observed, amusing choreography as she rejected all the men on stage in favour of an unknowing Wilhelm; and the chorus, in Fehr’s hands, also created spectacular tableaux in café and theatre scenes, albeit slightly awkwardly. But the overall problems with Mignon remain: like a doll you have to shake hard to make its eyes open, Mignon will calmly suck up all a director’s energy and ideas, and still only stumble across a stage.

I still found myself drawn in eventually, rather like a bad film that you accidentally light upon while scrolling through the TV channels with a hangover, and find yourself still watching 45 minutes later, inexplicably mesmerised. And I even found a few tears starting to my eyes: not when Mignon and Wilhelm declared a love we never felt was real, but rather when old Lothario shook hands with his ancient steward after years of wandering Europe, his mind lost in grief. But if this really was all opera had to offer today, I would give up.