Maybe, just maybe, Anna Netrebko’s advocacy of Tchaikovsky’s last opera – namely this recording (made live in Essen) and the rest of the grand European tour which accompanies it – will finally bring a heartfelt and glorious piece out of the cold and into greater currency. It is unique in so many ways but most of all in the sense of the private enclosed world that it enshrines. We are inside the unseeing Iolanta’s head and heart. Those dark, veiled woodwinds (echoes of Manfred) that cautiously lead us in, the archaic chamber-like string textures that promise well-being in the unfolding first scene. These are the first indications that this is first and last a piece about feeling, about ‘seeing the light’ in the spiritual sense.

Netrebko – whose round of glossy (and no doubt lucrative) celebrity concerts has seemingly preoccupied her of late – has never been better than here, where her head and heart are so self-evidently engaged. Her opening ariosa establishes the glorious complexion of her voice – a creamy, dark coloration extending unblemished throughout the range. It is her inwardness, of shared confidences, that are as affecting as the eventual full-throated rapture of the piece. She clearly adores it and feels deep communion with it – the sound, the poetry, of her native language, the ache of Tchaikovsky’s music. Emmanuel Villaume and the Slovenian Philharmonic Orchestra both embrace and illuminate it with distinction. How shrewd to add a French sensibility into the mix just as Tchaikovsky invoked medieval France through Russian sensibilities (and his own innate classicism). The refinement of Villaume’s conducting is a constant source of delight: it nuances and tempers even the most wholehearted flights of fancy.

The scene in which Iolanta and the Burgundian knight Count Vaudémont fall in love and most especially the moment Vaudémont at last realises that Iolanta is blind is marked by a penetrating passage for strings invoking his shock and silence. Netrebko’s response to this is extraordinarily touching, infused with a fear that he, like every other visitor, will leave her in her doting father’s protective solitude. Vaudémont is sung with lusty relish by Sergey Skorokhodov, one of those fabulous heroic Russian tenors with a sensationally full-flooded top which you just know is what Tchaikovsky had in his mind’s ear when he wrote roles like this and Herman in The Queen of Spades. As light begins to flood the score with the burgeoning of the lovers’ feelings for one another, the tune Tchaikovsky unlocks is almost child-like in its affirmation. ‘What is light?’ asks Iolanta. ‘Creation’s first-born’ replies Vaudémont. The thrill of these two voices locked in their musical embrace is quite something – as is the overspilling orchestral release in their wake. We are truly in this moment in the presence of Tchaikovsky’s greatness.

Every voice has been carefully selected to ensure that there are no weak links here. Vitalij Kowaljow as King René has his moment in a thematically significant ariosa while the preening and rather shallow Robert – the other Duke of Burgundy promised to Iolanta but in love with another – is sung with selfish ardour by Alexey Markov. There’s also a splendid contribution from Lucas Meachem as the Moorish physician Ibn-Hakia.

For sure there is, as I implied earlier, what some might regard as an overtly ‘primary’ response to the work’s resolution – a folk-like innocence and naiveté in the structuring of its happy ending – but as ever with Tchaikovsky the surface uplift betokens a deeper eloquence which all but the totally jaded will embrace.