The infamous black cocktail dress has returned to Covent Garden, now inhabited, against all expectations, by Deborah Voigt herself.

You may recall the saga of Ms Voigt, one of America's more substantial sopranos, being sacked when this Ariadne was new in 2002 - at the time she was several sizes too large for the dress.

Having garnered sympathy from those, not least in her native country, for whom dramatic verisimilitude has a lower priority than sheer vocal beauty, Voigt was gracious enough to accept Covent Garden's offer to return, once she had lost enough weight, with the help of gastric bypass surgery, to fit the production - and that dress.

Voigt has a gleaming tone with a touch of steel, ideal for Straussian roles such as Ariadne. Her diction is crystal-clear and her animated line projects the words with genuine feeling for their significance. There's a nice irony in that the work is in part about the pressures to which great art is subjected.

Christof Loy's production, sharply revived by Andrew Sinclair, brings out the undesirability of seigneurial diktat, but also plays with the tricky issue of sexual allure in both art and life. Gillian Keith's Zerbinetta spends much of the Prologue wiggling her bottom in tight jeans, often with only a bra above, the better to display her assets.

The production thus now adds its own witty critique to the cocktail dress incident but Keith, making her mainstage début, is in vocal terms, too, an impressively agile coloratura soprano, secure in the stratosphere. Robert Dean Smith is in good form with an heroic Bacchus, while Kristine Jepson is an outstanding Composer, evoking the inspirational quality of the creative artist in streams of Straussian eloquence.

There's strong support from members of the Jette Parker Young Artists Programme and others in the comprimario roles. The whole thing is tied together with the mastery and sensitivity we have come to expect from the newly knighted

Mark Elder.

One could quibble over minor details and the singers new to the production will doubtless bring even more to it in due course. But this was a life-enhancing evening and a triumph for both Voigt and the Royal Opera. The house has reasserted its conviction that theatrical values in opera are no less important than musical ones. Deborah

Voigt has given dramatic and visible credence to that principle.