Actually as part of the 'Good Friday' peace deal in the late 90s, the Republic of Ireland removed their claim to Northern Ireland from their constitution. This was even approved by Irish voters in a referendum (required to amend the constitution). So Northern Ireland is not disputed territory.
Labor court orders Jerusalem light rail operators to return to work (Haaretz)
from the article: Britain bans ad promoting tourism to Israel for blurring 1967 borders