Is this talking about Republic of Ireland, the southern area.
The northern part, Northern Ireland, old Ulster, isn’t it Catholic and where the Catholics went?
The Republic.
The North used to be overwhelmingly majority Protestant, with the Presbyterians being the biggest single denomination. The proportion of Protestant to Catholic is coming closer to parity now (2011 census showed respective 41.6 percent to 40.8 percent), with “no religion” and “religion not stated” being reported in higher numbers. Presbyterians and most other Protestants identify as British.