I mean, I really do see the difficulty. It is Verdi’s roaring melodrama, with its fatal baby-swapping only a madman could have dreamed up — take a bow, Antonio García Gutiérrez — its rum-ti-tum armies of over-jaunty spear-carriers, its shameless coincidences and ecstatically self-harming crew-list. It flirts so lewdly with parody that it’s no surprise to find their bastard offspring popping up so frequently in the work of W.S. Gilbert and co. Since the audience is going to giggle sometimes no matter what you do, perhaps you really might as well throw them a sop or two to make them feel better about it.

This is the not-in-itself too unreasonable approach of director Adèle Thomas to a piece which for a variety of reasons doesn’t often come off in the opera house. The main one — and no apologies for repeating Enrico Caruso’s chestnut, because it’s true — is that it needs “the four best singers in the world”. None of Covent Garden’s leading quartet is near that, though they have their moments. (We were supposed to have got Anna Netrebko and husband Yusuf Eyvazov, which would have been nice, but evidently their self-denunciations and rejection of their homeland have not been virulent enough for the weaselly Zhdanovs at Covent Garden). Ms Thomas cunningly seeks to finesse this lack of vocal quality and heft with a programme note averring that great acting is more important, but signally omits to follow through. Actually, physical acting has never been a requirement in Trovatore (it’s all in the voice), and the chosen mise-en-scène of a steep staircase is designed to keep them rooted to the spot and not move a muscle. So much for that, then.

Leonora, the sacrificial bunny, mistakenly believes she’s starring in a chivalrous romance

To be fair, it’s a hard working staircase: sometimes a football terrace, sometimes the ramparts of Spamalot, sometimes (perhaps, even) a harmless hillside, but mostly the exit-ramp to hell. Behind, there is only pitch darkness. This is about right: Trovatore is the blackest, gothiest of operas, with a peculiar spiritual quality of its own that not everyone appreciates. Its dram pers are crazed solipsists, each already ensconced in their own hells: mad gypsy Azucena, so obsessed with vengeance she will sacrifice her son for it; that (supposed) son, the insurgent troubadour, Manrico, determinedly doom-bound, spurning every whiff of happiness in favour of self-destruction; Count Luna, maddened by his desire to possess the Leonora who loves his bitter enemy Manrico (who is actually the brother he believes dead … ). Then there is Leonora, the sacrificial bunny, mistakenly believing she’s starring in a chivalrous romance, not a snuff movie, who finally joins the party by damning her soul twice over.

This is heady stuff, controlled by Verdi into arias of such atrocious spiritual desolation and loneliness you can hardly breathe. The libretto drops heavy hints: each of them is “deserto sulla terra”; human hope is “l’ombra di un sogno”; they can howl to God as much as they like, nobody’s listening — but they don’t really get it.

There are fleeting moments when the director seems to take this seriously. She momentarily clears the stage of her capering demons and the hysterically arm-waving chorus, leaving the characters there with their voices and the appalling, malevolent emptiness of the universe. With Tony Pappano’s brilliant orchestra — the star of the evening in every way, with the versatile chorus of roaring blood-maniacs and otherworldly nuns a good second — underpinning every aria with the most forthright and stylish foreboding, those moments are pretty good. Even the various inadequacies of the singers vanish into the force-field of Verdi’s nihilistic black hole.

Jamie Barton, singing Azucena, puts in a peculiar panto turn

They really are fleeting, though. The rest of the time something stupid is reliably happening, without anything original about it: the silly Python soldiers, the descending cut-out clouds, the medievalist fooflah, the Bosch quotes. Something about the costumes and chorus behaviour tells me Ms Thomas has seen the work of the genius German artist-director Achim Freyer, who can mix up a Big-Top dreamworld into a true-Gothic archaic universe and weave instant magic, but here we get a lot less than the shadow of that dream. She is a good, imaginative, funny director, pretty new on the block, but currently over-exposed; those who have served more authentic apprenticeships might be forgiven for feeling resentful.

Given the accumulated tasks, the singers do their best, but it’s no better than serviceable, and most of the voices are too small. Marina Rebeka has a crystalline focus, but it’s not a very charming voice; even Ludovic Tézier — a very eminent Verdi baritone, singing Luna — sounds rather clumsy in his arias, better in the passionate recitative. Jamie Barton, singing Azucena, puts in a peculiar panto turn. Sure, this whacked-out death-maniac doesn’t have to be the epitome of bel canto, but a bit of actual singing wouldn’t hurt; I thought wistfully about what one of those foghorn Russian mezzos could do with the role. In the circumstances, the stand-and-deliver of the others is something of a relief. When she does actually sing, as in the tragic remembrance-of-happy-times duet she has with Manrico as the final bloodbath approaches, the full Verdi finally comes through.

Yes, Trovatore is an outrageous piece, its surface quite ridiculous — we hardly need the director to be at such pains to tell us that. You need balls at the best of times as a viewer to carry on through it all to the fabulously concentrated core. It’s an old story: this staging was first seen by the sophisticates of Zurich, where it is obligatory to have a Konzept of varying silliness. German-speaking audiences have been browbeaten into putting up with this sort of thing, but they hardly ever work when they get here. We can talk another time about why that is. This one’s by no means the worst, and I really quite enjoyed it, but boy, was it ever an effort.