Carroll received her acting training at the Central School which later became the Webber Douglas Academy of Dramatic Art London, appearing in three plays in London's West End and a film, Midnight Episode, by age 20. She made her Broadway debut in Separate Tables by Terence Rattigan. She moved to the U.S. during the 1950s, touring and performing on Broadway and co-founded, with Dermot McNamara, The Irish Players, a repertory theater company in Manhattan.
