Rats: that’s what Hans Neuenfels’ production of Lohengrin will long be remembered for. This season marks the final Bayreuth outing of his imaginative revisioning of Wagner’s last romantic opera, a staging which made its debut there in 2010. Even now, there is little critical consensus as to what precisely the laboratory setting means, or why the chorus should now be rats, now various rat-human hybrids, and finally humans with futuristic shaved pates. Like the best theatre, it provoked a riot of plausible speculation, and like the best operatic settings, it did not interfere with our appreciation of the singing. Musically, the star turns were from Klaus Florian Vogt in the title role and Petra Lang as Ortrud, but everyone from Samuel Youn’s Herald up was in good voice. The orchestra was ably led by Alain Altinoglu, and the chorus was especially impressive throughout.

After the ethereal strings had begun to descend from the stratosphere in the Prelude, the curtain went up on a man (subsequently revealed to be Lohengrin) trying in vain to open double doors in the back wall, something that he only succeeded in doing at the end. In the interim, his exertions pushed the back wall further upstage, revealing a series of iron grills along the wings. With the start of Act I proper, the rats came swarming out of these into the aseptically white-lit space, each individually numbered. Whether in their furry costumes, or after they stripped these off later to reveal yellow suits (but keeping their rat heads), the chorus never remotely suggested völkisch power, in keeping with Neuenfels’ belief that the choral numbers were not “martial pantomime or fascistic hate-mongering”. The curse was taken off even the “Sieg! Heil” at the end of the Act. King Heinrich, too, was not the wise overlord of traditional productions: the reliable Wilhelm Schwinghammer made him a nervy king of the mad, starting at shadows as if on a bad trip.

The relationships between the four principals were largely left intact, although there were many scenic innovations in how they were presented. Friedrich’s perjured narrative was accompanied by an animated video of a rat-version of his story entitled “Wahrheit 1” (Truth 1). Elsa entered pierced with arrows, and delivered the “In lichter Waffen” part of her monologue lying prone on the stage. Annette Dasch has not got the biggest voice, but she was always comfortably audible without having to strain. Lohengrin’s arrival as her champion can be a moment of high kitsch, but rather than be towed by the swan, he preceded a funereal procession in which the swan was borne aloft in a mini-boat by rats. Klaus Florian Vogt’s opening apostrophe “Mein lieber Schwan” was miraculously restrained – he managed to sound like a lyric tenor, before asserting his formidable Heldentenor credentials later on. His fight with Friedrich was accompanied by another rat film, and the final rejoicing was counterpointed with a sight of the now featherless swan lowered from the flies.

In Act II, the wrecked coach/dead horse of Friedrich and Ortrud was seemingly still within the lab environment, although Elsa’s glass-box room suggested that she was in another level of confinement. Of interest in terms of the experimental set-up was the increasing independence of the ‘subjects’: earlier, the silent hazmat-clad figures who occasionally appeared seemed in total control, but now were as frequently defied by those on stage. Ortrud comes into her own in this Act and Petra Lang gave an utterly convincing rendition of the demoniacal sorceress, her dark-hued yet flexible voice providing suitable colouring for her character’s pagan fulminations. She was ably supported by Jukka Rasilainen as Friedrich in the first part of the scene, and later on she and Dasch provided ideal vocal foils for each other.

The big choral scene later in the Act saw women in 1950s dresses (and rat-tails) paired with men in black-tie (with rat-hands/feet). Aside from a couple of tiny coordination issues with the orchestra, the chorus was of the same formidably high standard as those in Act I. One of the scenic innovations here saw the hazmat team disassemble the cross that stood for the Cathedral, but Lohengrin wrenched the parts from them and held it together at the final curtain.

Both dramatically and musically, Act III was probably the highpoint of the evening. After the famous bridal procession (the middle parts of which felt ever so slightly pushed in tempo), the love scene between the newlyweds was brilliantly worked out, their body language showing their evolving distrust. The now rat-Friedrich was disarmed and killed in a deliberately unrealistic slow-motion sequence. After Lohengrin’s revelation of his origins and name, the gigantic question mark on the back wall turned into an exclamation mark, not untypical of the touches of humour that the production as a whole managed to find in an essentially humourless work. The most disturbing moment was the birth of a homunculus Gottfried from a gigantic egg at the very end of the Act. As everyone else collapsed, Lohengrin walked slowly towards the footlights, a reversal of how the opera opened. Provocative and thought-provoking, this production afforded both intellectual and auditory pleasures, and so by any standards, counts as a success.