Callas’s Anna Bolena at La Scala in 1957 was one of the absolute highlights of her extraordinary career. The performances brought new life to a bel canto opera that had long fallen out of favour. The central role was ideally suited to her talents and she once again had Luchino Visconti as her director. Anna’s rival, Giovanna Seymour, was sung by one Callas’s most trusted colleagues, the superb mezzo-soprano Giulietta Simionato. The conductor, Gianandrea Gavazzeni, described the production as “a complete revelation of what I have always felt should be the ideal collaboration between stage and music”.