Yes, I think my belt and braces drafting of making it clear NI is not included if a contractual territory is Ireland is probably safest.
Wiki says as follows so it sounds like until 1998 (which irelatively recntly I was 37 then ) the British Govenrment used "Eire" which is probably where a lot of English people got it from - Eire and Northern Ireland and that all that changed in 1998.
"Name
Main article: Names of the Irish state
The 1922 state, comprising 26 of the 32 counties of Ireland, was "styled and known as the Irish Free State".[16] The Constitution of Ireland, adopted in 1937, provides that "the name of the State is Éire, or, in the English language, Ireland". Section 2 of the Republic of Ireland Act 1948 states, "It is hereby declared that the description of the State shall be the Republic of Ireland." The 1948 Act does not name the state as "Republic of Ireland", because to have done so would have put it in conflict with the Constitution.[17]
The government of the United Kingdom used the name "Eire" (without the diacritic) and, from 1949, "Republic of Ireland", for the state;[18] it was not until the 1998 Good Friday Agreement that it used the name "Ireland".[19]
As well as "Ireland", "Éire" or "the Republic of Ireland", the state is also referred to as "the Republic", "Southern Ireland" or "the South".[20] In an Irish republican context it is often referred to as "the Free State" or "the 26 Counties".[21] "