This semi-staged collaboration between conductor Simon Rattle and director Peter Sellars, old hands at Pelléas et Mélisande, was first seen last month in Germany where the orchestra was the Berliner Philharmoniker. Now, in a sort of artistic bridging exercise, the show has travelled to London for two further performances and an LSO Live recording, this time with the maestro at the helm of his new best friends.

Before the performance Rattle paid touching tribute to Pierre Boulez, the colleague to whom he and the London Symphony Orchestra wished, he said, to “devote” (a good word, so much more engaged than ‘dedicate’) this performance of Debussy’s opera. Whether his late mentor would have appreciated the voluptuous, lushly upholstered interpretation that followed is debatable. Maybe he would; his own recording of Pelléas has a surprisingly unbridled sweep; what it also possesses, though, are translucence and a touch of astringency, neither of which was discernible in Rattle’s rhapsodic reading.

Yet this was rapt, magical performance – often spellbindingly so. Rattle has lived with this opera for many years and he delved sensitively into its mille-feuille layers. Time and again he would draw the tiniest melodic fragment from its habitual bedding and let it glitter like a jewel. It helped that the LSO was configured theatrically rather than traditionally, with the first violins shifted to the centre and an arc of harder-voiced instruments around the edges. This layout, much in line with the composer's own stated ideal, sharpened the impact of Debussy’s orchestral storytelling and rendered the production (about which more anon) all but irrelevant.

It also helped that Rattle fielded a cast of extraordinary distinction, even though none of them were native Francophone speakers. A ‘Soloist of the Tölzer Knabenchor’, discreetly wired for recording, sang Yniold with bell-like clarity, confident stage presence and a dazzling sense of idiom. (Why European children’s choirs persist in their somewhat arch non-attribution of soloists is particularly baffling when Master X is the sole child performer. At least he is named on the Barbican website, if not in the programme, as Elias Madlër.) Franz-Josef Selig was a gentle, dignified Arkel, and no less a figure than Bernarda Fink contributed a moment of alto delight as Geneviève, the mother of Golaud and Pelléas.

Star baritones Gerald Finley and Christian Gerhaher were vocally resplendent as the two brothers, the former’s Golaud gruff yet fluently expressive and more than usually brutal, the latter subtly eloquent in projecting the agony that suffuses Pelléas’s brief ecstasy.

The unhappy love triangle was completed by Magdalena Kožená in a role that sits as well for a mezzo as it does for a soprano. As Mélisande she was less persuasive than her male colleagues, however, and her attempts at absence were more akin to saucer-eyed gurning than, as Arkel puts it, “l’air étrange et égaré de quelqu’un qui attendrait toujours un grand malheur” (‘the strange, distracted look of someone who lives in expectation of great misfortune’). Perhaps her facial tricks were a conscious decision designed to make her innocence appear contrived, but it was still overdone. Nevertheless, Kožená sang with undeniable beauty and a gratifying echo of Debussy the mélodiste, albeit in garbled French. It’s just that she would have achieved so much more by doing less.

As indeed would Sellars, whose production sought to solve all mysteries. But Pelléas et Mélisande is like a coral lagoon: its secret lies deep, barely within reach, and a good director will extend a careful hand towards it. Sellars, instead, whipped up the waters with a hundred ideas and thereby muddied them. Is Mélisande a schemer or a child-woman who longs to be Yniold’s playmate? Does she drop Golaud’s ring through thoughtlessness or throw it petulantly into the fountain as an act of defiance against her abusive husband? And what’s with the Shepherd (Joshua Bloom)? Out of nowhere, and with no dramatic context, he appears fleetingly as a people smuggler with a cellphone. Do we infer, by extension and with an inward groan, that Mélisande is an asylum seeker?

All this, the odd and the inspired, was enacted around and among the musicians using every inch of the extended Barbican Hall platform. Ben Zamora’s lighting (spotlit pools plus some chic vertical light sabres) were all it took to suggest changes of location; Rattle and the orchestra did the rest. Roll on the recording.