Hanley trained as an opera singer at the Juilliard School. A teenage protégé of Leonard Bernstein, she was a soloist in the Great Composers Series singing his work Glitter and Be Gay (Candide). Much of her early work was in musical theatre prior to transitioning into TV and Film. She played Polly Peachum in a London production The Beggar's Opera which was part of London's West End summer (limited run) season Open Air Theatre productions at Holland, Cannazaro and Regent's Parks in the 1990s