André Tchaikowsky is best known for having left his skull to the Royal Shakespeare Company, and for appearing posthumously with David Tennant in performances of Hamlet. His love of Shakespeare was shown less melodramatically during his lifetime by his operatic setting of The Merchant of Venice, a play which allowed him to explore elements of his own character as a gay man (Antonio is shown as overtly gay and ends the opera back on the psychiatrist’s couch) and as a Jew who escaped as a child from the Warsaw Ghetto. Shylock is the central character of the play (it is Antonio who is the Merchant of Venice – Shylock is merely a moneylender) and in the opera it is Shylock, performed with great musical and dramatic power by Lester Lynch, who is the harsh, unforgiving figure at the heart of an unromanticised, commercial Venice.

Ashley Martin-Davis’ set for Keith Warner's production avoids all clichéd references to Venice: no gondolas or cupolas in sight. Instead, we are in a bank-vault, with three safes in gold, silver and lead already waiting for Portia’s quiz for her suitors. The costumes are vaguely Edwardian, with Shylock in a quite literal gabardine, his Jewish identity marked with a skullcap. More subtly, there are numerous visual references to the Jewish prayer-shawl with its blue stripes, which turn up in rugs and clothing fabrics, as if the Jewish presence in Venice has infiltrated many aspects of the city’s life.

Antonio’s entry was hampered by Martin Wölfel’s thin, almost inaudible countertenor. Little diction came across from him, and in general the presence of the text in the surtitles was a help. Antonio’s hopeless, unfulfilled love for Bassanio leads him to pledge a bond to Shylock to secure a loan against Bassanio’s merchant ventures. Meanwhile, Shylock’s daughter Jessica elopes with her lover Lorenzo, abandoning her father and her Jewish faith, while taking her jewels and money with her. Shylock rants about his daughter and his ducats, and the brutal music accompanying his diatribe makes him seem thoroughly selfish and venial, with no softening of his character or so much as a glimpse of humanity. Even his anger at the loss of a turquoise ring, the last gift from his late wife Leah, is more about the stone than the sentiment.

Portia’s realm in nearby Belmont is musically different from the brusque commerce of Venice. Woodwind and strings are allowed to be lyrical, the brass is toned down, and there is even a stage band with the Renaissance sounds of harpsichord, lute and recorder to accompany "Tell me where is fancy bred?" This pretty pastiche has the feeling of 1920s English stage music, and the song was deliciously sung by Fiona Harrison-Wolfe in cabaret attire. Portia and Nerissa also seemed to be on the verge of a lesbian relationship, wrestling intimately before dusting themselves down for the comical trial of the three suitors. The Prince of Morocco, danced by Wade Lewin, finds a skull in the golden casket – I wondered if it was Tchaikowsky’s own, on loan from the RSC – and the Prince of Aragon finds a mirror.

Bassanio is the lucky one, and picks the leaden casket with the portrait of Portia. During this act, the vocal lines emerged much more clearly from the lighter orchestral textures, and had more easily memorable melodic outlines (though not much more memorable) with Sarah Castle’s soprano particularly effective. "I am amazed," Portia declares, and the whole set is a maze of clipped box, mirrored at the back of the stage with some clever video trickery: altogether an ingenious staging which would work just as well for the spoken play.

With Shylock’s attempt on Antonio’s life (brandishing a practical-looking scalpel) the third act returned to the harsh music of the first act, even Portia (disguised as a lawyer, with Nerissa as her clerk) taking on the stark tones of commercial Venice. Miklós Sebestyén made a splendid Duke, presiding over the trial and allowing Portia to win her argument and secure Shylock’s downfall. In the epilogue, the prostrate figure of Shylock dominated the stage, while the final comedy of lost rings (complete with a corny Wagner quote) played out, reminding us that this difficult play, with all its undisguised anti-Semitism, is billed as a comedy. If it was André Tchaikowsky’s skull in the golden casket, it certainly had the last laugh.