I can inform you of at least two Mc Giverns in Florida, my parents, who own a couple of properties out there. My vauge knowledge of my family tree is that my grandparents lived in Belfast with my great grandparent having some sort of involvement with the fabrication of the Titanic (the chains I believe). My father (John) was also born in Belfast but moved to Chelmsford in England, (I presume in the 60's). I was born in Gloucester in 1980 but only lived there for a short while before moving to Cambridge, UK where they have been based for the past couple of decades. I have since moved to London.
As I say that is a somewhat potted history but I hope that adds another branch to the tree!