Vanessa, Barbican, London

In the opera, she locks herself away in her secluded mansion for 20 years, covers the mirrors, sees no one. As in art, so in life. Vanessa, Samuel Barber's Pulitzer prize-winning opera, has been more than 20 years in seclusion. Try nearer 50 years. Still unstaged professionally in this country, she remains one of opera's inexplicably unsung heroines. A packed house greeted her at this concert performance at the Barbican. A new recording is in the stores, another with this cast and orchestra - the BBC Symphony - is on the way. Leonard Slatkin, its conductor, is a passionate advocate. Perhaps, at last, Vanessa is ready for her close-up.

Barber waited until he was 47 before attempting opera at all. Vanessa was his first-born. So, what took him so long? For one, he was waiting for the right libretto. It came from his lover/partner Gian Carlo Menotti, and you may question (and many do) that it was worth the wait. It's arch and purple enough to betray the fact that English was not Menotti's first language. But as drawing-room drama writ large, intimacy in opulence, you can see how it was perfect for Barber, who often conceived small but liked to project large. His well-upholstered orchestra seems to symbolise the burgeoning emotions that overwhelm his characters. The accent may be European but the manner is American: overwrought and over here. It's Richard Strauss goes to Hollywood.

Another reason Barber waited so long was in order to thoroughly hone his craft. He was a fabulous orchestrator, but voices were his passion. Vanessa is self-evidently wonderful to sing. Barely is the opera under way when the two female protagonists, Vanessa and her niece Erika, are rewarded with back-to-back arias. And they are both corkers, especially when sung by two of the best singers gracing the international scene - Susan Graham (Erika) and Christine Brewer (Vanessa).

Graham proved effortless in the high tessitura, frequently belying her mezzo status. She has a wonderfully immediate way with words, and almost had me buying Menotti's fanciful text. Brewer, meanwhile, fresh from her recent triumph in Strauss's Four Last Songs, used her Straussian ascendancy to wonderful effect, holding on to her melismatic phrases like a lost love regained. William Burden's suave Anatol used his long phrases like enticements - the words "life is so brief" were spun out in anticipation of prolonged pleasure. Then there was Catherine Wyn-Rogers, quietly indomitable as the Old Baroness, and Neal Davies as the Old Doctor, combining a sharp nose for comedy with notable lyric beauty.

Uncover the mirrors. It's time that Vanessa took pride in herself again.