Thanks for the further replies. I have made some enquiries on some British sites today so hopefully someone there may know more. It certainly sounds like it will be a difficult task as it is so difficult to prove. I have no evidence other than verbal evidence from my parents and midwife and a few of my parents other friends.
In regards to birthright citizenship the laws state that those born on the island of Ireland (ROI or NI) on or before 31/12/2004 are automatically entitled to Irish citizenship (regardless of whether or not there parents or grandparents are Irish citizens).But those born on or after 01/01/2005 are only entitled to Irish citizenship if their parents or grandparents are Irish citizens. So i believe i am definitely entitled to it.
They only got rid of birthright citizenship for those born on or after 01/01/2005.