The Church of Ireland describes itself as
The Church of Ireland considers itself Catholic because it is in possession of a continuous tradition of faith and practice, based on scripture and early traditions, enshrined in the Catholic creeds, together with the sacraments and apostolic ministry. However, the Church of Ireland is also Protestant, or Reformed, since it opposes doctrines and ways of worshipping that it considers contrary to scripture and which led to the Reformation.
The Church of Ireland, as a Reformed and Protestant Church, doth hereby re-affirm its constant witness against all those innovations in doctrine and worship whereby the Primitive faith hath been from time to time defaced or overlaid, and which at the Reformation this Church did disown and reject.
When the Church of England broke communion with the Holy See, all but two of the bishops of the church in Ireland followed the Church of England, although almost no other clergy did so. The church then became the established church of Ireland, assuming possession of most church property (and so retaining a great repository of religious architecture and other items, though some were later destroyed). The church explains its possession of so many of the ancient church buildings of Ireland by reference to the precedent set by Emperor Constantine the Great in the 4th century: