Hippolyta gets 43 bars of music in Britten’s A Midsummer Night’s Dream, many of them confined to brief asides or else lost in ensembles, so the singer who plays her seldom rates a mention in reviews. Yet Ida Ränzlöv survived a catastrophic misreading of Shakespeare’s text by director Liam Steel, about which more anon, and sang a cameo where every note was flavoured, every word weighed for its subtext and every action measured. Hers was the performance that stayed with me as I left the Britten Theatre after a fascinating if frustrating evening.

Fascinating for many reasons, not least its coincidental juxtaposition with ENO’s revival of Robert Carsen’s taut and meticulous staging of the same work. The Royal College of Music has fielded at least one, possibly two, outstanding casts for a production that the tireless Michael Rosewell is conducting in between performances of Il tabarro and (Steel again) Gianni Schicchi for English Touring Opera. On a musical level it is astonishingly accomplished, and the work feels completely at home in the intimate setting.

And frustrating? That’s the concept. Steel had a eureka moment when he decided to set the Dream in a seedy Weimar cabaret (and Sally Bowles creator Christopher Isherwood’s friendship with Britten adds extra spice to that idea) but he's failed to follow it through. George Longworth’s Puck is a kind of Emcee, although not a dangerous one – more a hangdog to Timothy Morgan’s terrifying Otto Dix Oberon – and the Fairies (another prime contingent from the ubiquitous Trinity Boys Choir) are wizened old men: ten Toulouse Lautrecs from Sin City. Yet, weirdly, there’s more sex in Carsen’s green playground than Steel finds in his neo-Kit-Kat Club. The place should reek of it; instead he plays it coy, and such rudery as there is feels tacked on. Moreover, he cannot solve the problem of the Rustics so he leaves them to it, intruders from another world.

Steel’s inspiration has the potential to be a wonderful Dream, dark and thrilling, but it needs work. It ought to dare the way Rufus Norris’ production of Cabaret dared, and let’s hope that before too long a professional company grants him the chance to explore the opera's darker places. That would also give him time to fine-tune physical performances by the four lovers, excellent singers all at the RCM but wilted by the kind of generalised acting that results from a lack of textual scrutiny.

Michael Pavelka once designed a potent Shakespeare Dream for the all-male Propeller Theatre Company (still my personal benchmark, for what it’s worth) and here, in tandem with sensational lighting by Andy Purves that makes literal use of smoke and mirrors, he creates a stunning new environment that’s dark, claustrophobic, surprising and mysterious. Countertenor Morgan, fabulously rich of timbre if not wholly at ease in Britten’s taxing lower reaches, and his Tytania (Harriet Eyley, magnetic, big-voiced and bright-toned) felt entirely at home here, while the black-lace masks of their ‘Shadows’ – a clutch of mimes – lent a welcome sense of preternatural menace. In a blissful inspiration by Steel, these semi-present creatures also served as the four translated limbs of the donkeyfied Bottom.

Timothy Edlin was a superb ass, first among six equals who together smashed the Mechanicals’ scenes. No praise is high enough for their efforts, even though Pyramus and Thisby, when it came, was spoiled by playing up rather than against its comedy. Surely the players need to think they’re acting it well? I didn’t laugh once, although others around me did; but that’s also because I was smarting from a wife-beating interlude that soured the entire last scene. Steel has taken the Duke’s line to Hippolyta “I woo’d thee with my sword / And won thy love doing thee injuries” as a green light for Theseus (Peter Edge) to knock his new bride around the stage, even though the rest of Shakespeare’s text suggests connubial harmony.

Musically one would be hard pressed to find a better matched set of Lovers than Lauren Joyanne Morris (Hermia), Josephine Goddard (Helena), Joel Williams (Lysander) and Kieran Rayner (Demetrius), nor a tighter orchestra than the youthful pit players whom Rosewell guided so impeccably through what can be a rocky score with its exposed writing and for the challenge of pitching the correct level of ensemble playing. This, as Bottom might say, was lofty.