Having looked into some requirements for gaining Irish citizenship (passport to the EU) I have discovered that to be able to use a great grandparent born there, your grandparent is automatically an Irish citizen, and your parent can apply for citizenship through foriegn born registration. If your parent did this before 1st July 1986, you can apply at any stage, provided you were born after 17th July 1956. If however Your parent did not register until after 1st July 1986, then you can only apply if you were born after they have registered.

Looks like I missed out on this one.