historical geographic location United Kingdom of Great Britain and Ireland Kingdom of Ireland 1542 1800 A client state of England and then of Great Britain that existed from 1542 until 1800. It was ruled by the monarchs of England and then of Great Britain in personal union with their other realms. The kingdom was administered from Dublin Castle nominally by the King or Queen, who appointed a viceroy (the Lord Deputy, later Lord Lieutenant) to rule in their stead. It had its own legislature (the Parliament of Ireland), peerage (the Peerage of Ireland), legal system, and state church (the Protestant Church of Ireland). Irish