It’s not long before he composes a song of his own, based on an incident that really happened to him and his brother. It is a huge success the first time he performs it, and he knows he’s found his calling in life. This is the night he meets Mary Duane for the first time.
He recalled every verse of the long, complicated love-song, a very old piece his mother used to sing, with classical allusions and multiple narrators. 'Macaronic' was the word for a song like that, its lyric alternating between Irish and English (O'Connor 93).
Later when he is in London, he finds that his Irish songs aren’t successful with the English. So he tweaks his song, “unpicking anything too disquieting or too noticeably Irish. Not a jot did it bother him to alter the ensemble. It was tailoring Galway remnants into East End swell-duds” (O'Connor 185). This altered version of the song gets the attention of a certain Charles Dickens, who asks Mulvey for more details on where he got the song. Mulvey comes up with an elaborate yarn of backstory that Dickens would eventually turn into Oliver Twist, if the story is to be believed.