The use of a surname as a Christian name is often used in Protestant families, indicating a connection to that family, usually a birth or other family connection such as a marriage somewhere or inheritance. The family of Persse in Galway was powerful and is well known (such as Lady Gregory who was born a Persse) and would have been an important connection to promote. There is a new book out called “The Persse Family of county Galway 1554-1964” by Gerry Kearney. 2016 and 414 pages so substantial. Unfortunately I don’t have this book myself.