Despite the attention inevitably given to Frank Castorf’s controversial, ‘post-dramatic’ staging of the Ring, these performances at Bayreuth have ultimately been about the music. Götterdämmerung maintained the strong vocal casting and impressive conducting of the earlier instalments in the cycle. Catherine Foster capped her portrayal of Brünnhilde with technical control, rich tonal colour and stamina that lasted right to the end of her Immolation Scene. Stefan Vinke, still sounding a bit nasal in tone, varied his expression in other ways and, in line with Castorf’s thinking, maintained the character’s immature bully-boy persona to the last.

Stepping in at just two days’ notice as Hagen, Albert Pesendorfer, replacing an indisposed Stephen Milling, made the part his own, his bass voice suitably dark and menacing, his presence looming and powerful. Markus Eiche, one of the most impressive of current Wagnerian baritones, brought out more of the aggressive in Gunther than we often see, while singing with unflagging suavity. Allison Oakes’s beehived Gutrune made a good impression and Russian mezzo Marina Prudenskaya was a sonorous Waltraute – her scene with Brünnhilde was one of the highlights of the evening. The trios of Norns and Rhinemaidens, overlapping in personnel, capped an almost ideal cast.

Marek Janowski’s conducting throughout has been a revelation – more energised and searing even than might have been expected from his two recordings of the cycle. A lot of this has been down to the sheer seductiveness of the Bayreuth Festival Orchestra – effectively a scratch ensemble amassed each summer with the best players from orchestras throughout Germany, but which maintains a distinct sound and aura of its own, from individual wind soloists and silken strings to the sheer power of the massed brass. There were a few moments of insecurity in this Götterdämmerung, most notably with the three Rhinemaidens missing their first entry, but the overall impression was of a masterly shaping of the music’s vast spans.

All the themes and superimposed ideas of Castorf’s interpretation come to fruition in this final evening: revolution, man’s exploitation of fellow man and of the earth’s resources (the oil Leitmotif is represented by a petro-chemical plant) and the looming power of capital (the final scenes play out before a facsimile of the New York Stock Exchange). There are more references to German history – the vassals wave the flags of the four postwar occupying powers, for instance, and much is made of the scarcity of food in those years. And the running ‘joke’ of allusions to great films across the cycle makes its mark with a pram tumbling down a long flight of steps in homage to Battleship Potemkin. With the Bayreuth proscenium being as tall as it is wide (Wagner may have been a dramatist ahead of his time, but he didn’t foresee widescreen), director and designer (Aleksander Denić) have been able to spread the action vertically as well as front and back, with arresting results given that each multi-sided set, on a revolve, is built like a labyrinth of interconnected levels and arenas of action.

A major, and largely uncredited role (at least in the printed programme book) goes to Castorf’s assistant and dramaturge Patric Seibert, who plays various silent roles across the cycle, from barman to revolutionary leader to roadkill corpse, and acts as a punch-bag for the various characters’ aggression while often providing comic visual asides (seen on live film) counterpointing with some of the more intense musical episodes. Castorf’s direction of character is certainly distinctive – there’s a streak of misogyny in his portrayal of most of the female characters as victims or sexually loose – only Brünnhilde seems to rise above this. But it is his recreation of Siegfried himself that is the most thought-provoking: this is a young man with no redeeming features – he doesn’t learn adult ways, he is licentious and prone to mindless violence, beating up a homeless man, and nothing he does warrants Brünnhilde’s faith in him; in other words, he is the very antithesis of a ‘hero’.

It takes a bit of effort to acclimatise to Castorf’s way of presenting things – it is designed to provoke and challenge. But it is effort repaid, as one comes to appreciate that his superimpositions are a web of interrelated Leitmotifs every bit as detailed and intricately worked as those Wagner weaves in his music. Sometimes it jars, sometimes it gels, but above all it makes one think – which was the composer’s own aim when he created his masterpiece.