L'incoronazione di Poppea
Walker's operatic debut was in 1969, as Ottavia in Kent Opera's production of "L'incoronazione di Poppea". She has also appeared in Britain with Glyndebourne Festival Opera, The Royal Opera, English National Opera, Scottish Opera, and abroad at The Metropolitan Opera (New York City), Lyric Opera of Chicago, San Francisco Opera, La Monnaie (Brussels) and the Vienna State Opera.