What drew Welsh National Opera to the music of billionaire composer Gordon Getty? Was it his long-established reputation as a composer of vocal music, such as his settings of Emily Dickinson, his cantata on Joan of Arc, or his opera, Plump Jack, based on The Merry Wives of Windsor? Or was it a promised donation of £1.2 million to the opera company from the Getty Family foundation? David Pountney, the Chief Executive and Artistic Director of WNO, as well as the director of this double bill of Poe-based (and somewhat po-faced) operas, has defended his decision on the grounds that Getty’s work is “beautiful, refined, sophisticated and atmospheric”. But the fact that the question has to be asked is an indication of the problems that occur when the boundary between donor and recipient becomes blurred. It is not that rich and powerful men have never shown signs of artistic talent: Pope Clement XI wrote a comic opera libretto, and Carlo Gesualdo, Prince of Venosa, was a great composer of madrigals (as well as a murderer). However, when a donation from a family trust is coupled with the performance of an opera by a member of the same family, it puts the work under unusual scrutiny.

How does Usher House stand up? Like the house, it doesn’t. It falls, and on two counts. One is that the libretto, written by Getty himself, is over-long, clumsily written, under-edited and full of absurd touches. There is, for example, a list of ancestral Ushers who don’t appear in Edgar Allan Poe’s original tale, and whose names would look better in illustrated books by Edward Gorey. The use of Poe as Roderick Usher’s friend who witnesses the events is clever, but would work out better if he had been shown to have some kind of relationship with Roderick or his sister Madeline (something Debussy manages much better in La chute de la maison Usher). Musically, the opera is mostly reminiscent of 50s B-movie scores, with spooky woodwind underlying a relentlessly tedious arioso, or heightened recitative, which plays heavily on rising fourths. The sinister Doctor Primus, sung by Kevin Short, is the only remotely compelling character, but all he does in the end is to reinforce the suspicion that no doctor in opera ever cured a patient. There is some pastiche dance music in the scene when Roderick invites his ghostly family to a ball (also not in the original story). The pitch of the entire opera rises to hysteria as the half-dead Madeline breaks out of her coffin in the family vault and – it’s the only phrase that fits – brings the house down.

The production of this and the following, much better but by no means good, one-act opera by Debussy is set wittily between large, moveable screens onto which are projected images of the magnificent Victorian folly Penrhyn Castle, near Bangor in North Wales. As a walk around Penrhyn, the production could not be bettered: mock-Norman arches vie for attention with polychrome pillars and starry vaulting. During the ghost scenes in the Getty piece, its halls are peopled by spectral Ushers, most of them showing the distinctive features of the uncredited Welsh actor, Dewi Savage, in a number of frightful wigs.

Debussy’s fragmentary La chute de la maison Usher is set similarly, but with monochrome shots of the castle, hugely magnified and effectively lit in the manner of a German expressionist film of the same period as the opera’s composition (1908-17). Debussy was hampered by the absence of much plot or dialogue in Poe’s story, and in writing the libretto himself, he centred it on a massively over-long monologue by Roderick Usher, which was sung splendidly by the huge-voiced Robert Hayward. Debussy’s doctor is a horror-movie figure with (in this production) a shock of Muppet-like ginger hair, the friend is a nonentity (well sung, however, by William Dazeley) and Madeline is the usual hysteric.

Robert Orledge contributes a useful programme note about his completion of the score – he holds himself responsible for 52% of it, but acknowledges that much of his half is derived from Debussy’s existing fragment. The rest is filled in with pastiche, drawing on Pelléas et Mélisande, La mer and other late works by Debussy. It is clear that Debussy’s difficulties in finishing the opera were much like those of Puccini’s with Turandot. The composer was not only suffering from cancer and had other family difficulties, but he was faced with a libretto which held irreconcilable ambiguities in the relationships between the characters. In the end, unlike Puccini, he gave up the struggle. It is questionable whether, unlike the cases of Turandot or Berg’s Lulu, the effort of completing it was worthwhile.