as per clause "Irish stamps issued before 1984 are official works and those over 50 years old are in the public domain." in Commons:Stamps/Public domain#Ireland
A work made by an officer or employee of the Government or State of Ireland in the course of his or her duties, created before 1st January 1974; or
A work made by an officer or employee of either House of the Oireachtas in the course of his or her duties, created before 1st January 1974; or
A sound recording, film, live broadcast or live cable programme of the proceedings of either House of the Oireachtas created before 1st January 1974; or
A bill or enactment of the Government of Ireland made available to the public before 1st January 1974.