 Under the name Mairín O'Farrell, she starred as Pegeen Mike in "The Playboy of the Western World" as part of an inter-varsity drama festival in Cambridge and Oxford in 1950.Collaborating with her sister Nuala, Charlton wrote an adaptation of Synge's "Playboy" as a ballad opera called "The heart's a wonder".It was performed in UCD's Aula Maxima in November 1957, after they had graduated.