Thanks Mary. Whilst I was aware of the Protestant naming habit, I had not come across any others with Persse as a first name. A look now at the 1901 and 1911 census show less than 10 people in the country with Persse as a first name and these are all male. There are only two births with the first name Persse on irishgenealogy.ie in the period 1864-1915, both entries relate to males also.
I was not aware of that book on the Persse family and will suggest to my colleague that he gets hold of it through interlibrary loan.