Nabucco, said Giuseppe Verdi, ‘was born under a lucky star’. It was both his last throw of the dice and his first undisputed hit, composed after the failure of Un giorno di regno and the death of his young wife and two children had driven him to abandon music outright. The story (at least, as Verdi told it) was that the director of La Scala had forced him to accept a libretto on the Biblical story of Nebuchadnezzar, and that when a page fell open on the chorus ‘Va, pensiero’ the muse returned. Citation needed, possibly, but there’s no question that the ‘Chorus of the Hebrew Slaves’ is one of those once-in-a-lifetime melodies; a tune (as Elgar might have put it) to ‘knock ’em flat’. It’s not every night at Covent Garden that the first curtain call — and the loudest applause — goes to the chorus.