Careful what you wish for. There can be no definitive way to stage an opera, and it’s the critic’s duty to keep an open mind. Still, we’ve all occasionally gazed at a white cube that represents an Alpine meadow, or watched a chivalric hero slouch across the stage in tracksuit bottoms, and felt our hearts slump. Then you pitch up at the Royal Opera House’s new production of Dvorak’s Rusalka and it’s as if some mischievous sprite has magicked you straight back to 1960.

At first, you don’t suspect much. It’s actually rather enchanting: deep forest darkness and an aerial dancer in rippling, shimmering robes, drifting into the light in an exquisitely realised swimming effect. Semyon Bychkov is in the pit, unfolding Dvorak’s prelude with a quiet command that leaves ample space for mystery. But then the lights go up and it sinks like a stone, visually at least. There are big green fake weeds and dancers scampering back and forth dressed as pond plants, arms curving wavily to indicate water. I swear I’m not making this up.

Many opera-goers, of course, will sigh with relief. It’s just not what you expect when the directors – there are two of them, Natalie Abrahami and Ann Yee – are also credited as ‘creators’ (back in your box, composer and librettist!) of a ‘poetic, contemporary new staging’. In Act Two, we’re in a perfume advert – a luxury hotel has been built over the woodland pool – and in Act Three we’re down with the bottom-feeders amid brightly coloured litter which is, we can agree, a bad thing. That seems to be the contemporary message: nothing, in other words, that The Wombles weren’t singing about five decades ago. The whole production is sustainable, apparently, and the programme has been printed with vegetable-based inks, so you can boil it for soup if the salad crisis intensifies.

The direction was as dated as the design. Characters stalked stiffly about the stage, extras mugged like it was their first day at RADA, and there was a fair bit of the old park and bark. It was all so wasteful: wasteful of Bychkov’s iridescent orchestra, of those ravishing aerial effects and of a cast that would be worth hearing in any Rusalka. Asmik Grigorian (Rusalka) has a plangent underside to her voice that conveys an eerie vulnerability, and the bloody scar on her back is one design detail that really does undercut the twee aesthetic. Rafal Siwek was a proud-sounding Vodnik, and if Sarah Connolly (a punky Jezibaba) was almost too genial, David Butt Philip’s singing as the Prince supplied a warmth that was missing from the direction. Ross Ramgobin, a singer who’s going places, made hay with the comic role of Hajny.

Opera North, meanwhile, is touring a new Ariadne auf Naxos, and it’s been updated to a 1950s film studio, complete with blue sky backdrop and spotlights for when the Prima Donna (Elizabeth Llewellyn – an inspired bit of casting, and she sounded lustrous) is ready for her close-up. The ensemble bustle of the Prologue zips along nicely, with John Savournin channelling John Cleese as the Major-Domo, Hanna Hipp finding light, shade and touching naivety as the Composer and Jennifer France reprising her naughty-but-nice Zerbinetta: currently one of the little marvels of British opera.

The only problem is the one that Strauss and Hofmannsthal left hanging, and which the director Rodula Gaitanou (like most directors) doesn’t quite solve: the opera’s intractable second act, which ditches almost all the relationships established in the Prologue, including the deliciously ambiguous frisson between Zerbinetta and the Composer. It wasn’t very ambiguous here, which made the lack of closure even more frustrating – even with echt-Straussian conducting from Antony Hermus.

The previous Friday, violinist Patricia Kopatchinskaja and pianist Joonas Ahonen played at Milton Court, and if you’re instinctively wary of PatKop’s cult following I can only say that she walked on in plain black and launched into Schoenberg’s 1949-vintage Phantasy with a vibrato so rich that this determinedly knotty music felt as sensuous (and as generous) as Strauss. There’s no timbre that Kopatchinskaja can’t draw from that violin of hers. She created echoing spaces around a tiny, wire-thin scrap of metallic tone in Webern’s Four Pieces, and dismantled and reassembled Beethoven’s Kreutzer sonata like some constructivist sculpture.

The house was packed, and it wanted encores. Kopatchinskaja exploded, shrieking, into a movement from Schoenberg’s Pierrot lunaire. More! She challenged us to guess the composer of a Schubert-ish salon piece – a tiny lemon-drop of a thing – and said we couldn’t leave till we’d got it. ‘Xenakis!’ shouted some wag. ‘Mendelssohn’ ventured another, and then everyone was at it while Kopatchinskaja kept shaking her head and waving her bow: ‘No! No! No!’ It turned out to be an unpublished work by the 17-year-old Gyorgy Ligeti, and reader, I called it.