Wotan built his Valhalla, and look what grief it cost that ducker-and-diver and those around him. Martin and Lizzie Graham have created their own Valhalla, a cross between Bayreuth and Glyndebourne, high in the windswept Cotswolds, and what a triumph is theirs.

Their long-cherished dream of producing a complete Wagner Ring cycle has been a long, patient time in the assembling, and now at last it has come to fruition, with no fewer than three presentations of the tetralogy tumbling one after the other in this, the composer’s bicentenary year - and the only professional offering in this country, to the shame of publicly-funded, more overbearing organisations.

Longborough has made such a virtue of necessity. The stage is narrow, so we train the eye upwards, and with such success. Very little space for scenic effects, so they make lighting all-important, with brilliant results from Ben Ormerod, complementing Kjell Torriset’s resourceful, economical settings - nets, grids, platforms, and three tripods, which had previously supported the vertiginous Norns, upended to show the collapse of Valhalla.

Where to put the orchestra? A Bayreuth-style pit delves Nibelung-style under the stage, much in Wagner’s own design for Bayreuth (Martin Graham used to be a wily builder), and there is space for 70 players.

Anthony Negus, having learnt the art of Wagner-conducting virtually at the knee of the wonderful Reginald Goodall, breathes and phrases with his well-coached singers, paces the paragraphs from his lovingly-rehearsed orchestra with an instinctively natural rise and fall.

Stage-direction was in the remarkably insightful hands of Anthony Privett, psychologically probing in order to turn Wagner’s pasteboards into characters of more than one dimension. The vastly experienced Phillip Joll was far more authoritative as the world-weary, ironic Wanderer into which Wotan turns himself in Siegfried. Wotan’s deluded vision expands worldwide, ending up with what he requires the wheedling dwarf Mime to do in Siegfried.

This was an amazingly engaging portrayal from the vastly experienced Adrian Thompson, no mere snivelling Semite as was Wagner’s intention, but a character exuding humour, pathos and desperation - with Wotan’s grandson Siegfried so horrible to this person who had brought him up.

Longborough was not alone in being shortchanged by its Siegfrieds. The eponym in Siegfried was Hugo Mallet, one of the most ringingly sustained performances I have ever heard, but woodenly conductor-fixated onstage. Jonathan Stoughton fixed with an ingenuous smile in Gotterdammerung, charming us out of the occasional vocal straining.

Neither of these alleged heroes was worthy of the truly remarkable Brunnhilde of Rachel Nicholls. It’s not so long since I admiringly reviewed this slip of a girl in Handel and Mozart, but she has now built herself into a Brunnhilde to be reckoned with all over the world.

Lee Bissett deserves a huge mention, portraying the three female victims of these operas: a genuinely terrified Freia, about to be given as booty to the giants (Fafner scarily Fagin-like, and perhaps tick-boxing Wagner’s anti-Semitism); a touching Sieglinde; and Gutrune, at last turning this poor cipher into a real character – and the only one left alive after the conflagration.

But the memory I have taken away from all four operas during their gestation, and which has fixed itself with me during this complete cycle, is the stealthy, silent ever-presence of what I like to call proto-Norns. These three slither, clamber and crawl all over the sets, observing with intense, unflinching concentration, presenting props, facilitating the scene-changes, doling out the yards of cloth which serve various purposes, and always there, like a Greek chorus, representing us. Had Wagner had the imagination to envisage this, he would have approved.