Part of the fun, it's true, of master classes is the tension between their avowedly pedagogic purpose and their entertainment value, which includes the possibility that they will turn into a blood sport. The trouble, though, with McNally's Tony Award-winning play - inspired by the master classes Callas gave in New York in the early Seventies when her voice and her personal life were in bad shape - is that it can't conceive of any aspect of such an event except in coarse, caricatured terms.
The character may be played by a woman but, in this work, Callas is, to all intents and purposes, a gay man performing a diva routine. Tossing out the bitchy one-liners with frightening articulacy ("don't ever wear anything like that before midnight at the earliest," she remarks to Susan Roper's ballgown-wearing soprano, shielding her face as if from some unseemly glare), she also shamelessly plays up to the audience, as when, waiting for the student to make an entrance as Lady Macbeth, Callas asks of the hall: "Does anyone know what time it is? I have a beauty-parlour appointment after this. I can't get a good wash and set in this city..." Opera queen in drag, you feel, rather than a queen of opera.
Nothing if not a vehicle for a leading actress (or actor), the show nevertheless puts its star in a somewhat invidious position. As the CDs of the actual master classes indicate, Callas tended to teach by example, her voice ravaged, but intermittently glorious, her dramatic instincts still electric. The recordings offer the chance to hear her perform snatches of male roles: for example, when she illustrates, unforgettably, the naked animal quality she feels should imbue Rigoletto's "Corteggiani, vil Razza Dannata". In the play, this essential element cannot be reproduced and Ms Lupone, having portrayed a silent screen star who can somehow sing like a diva in Sunset Boulevard, is now in the equivalently paradoxical position here of playing an opera goddess who barely croaks out a note.
Instead, Callas's own voice flares out from the speakers during two extended sequences where the singer flashes back to the triumph (eg of the first night of La Sonnambula ) and traumas (Onassis forcing her to have an abortion) of her past and the theatre is engulfed with projections of the La Scala auditorium. In these cliche-ridden passages, Lupone has to rely on intensity of facial expression and gesture (come back Norma Desmond) as she moves between melodramatic despair and vindictive exultation. It's significant that the best dramatic insight this Callas imparts is through a piece of business. Lady Macbeth, she says, can enter with her husband's letter screwed up in her hand, as she would have ravenously committed its contents to memory. Lupone is a class act, but you still can't believe that Callas's singing voice could ever have emerged from the character she and McNally create. Besides, her gender is against her. Me, I'm waiting for the revival with Hinge and Bracket.
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