You asked that I let you know how we got on with our trip, and David's quest to find out more about his family roots. Well - it couldn't have gone better! We loved Ireland, and drove from Dublin, to Donegal, Derry, the Northern Ireland Coast including the Giants Causeway, Sligo, Ennis, Wexford, Ring of Kerry and Cork, as well as other stop-offs. Before our trip, a number of friends had told us that Ireland was magical, and they were right.
And then - thanks to Sinead responding to this site - we met family members David never knew he had. In Laghey is a Spa petrol station, supermarket, lawn mower showroom, cafe etc, under the Robert Kee umbrella, run by the sons Desmond, John and David (another!) It was confirmed that their great-grandad was David's grandad's brother, so we heard lots of family stories, saw photos and documents, and managed to make sense of some of the family history. Desmond took us to the church in Laghey where David's grandad was christened, which was moving in itself, but it was also a huge moment to be taken to the townland of Moyne to see the homestead (on the photograph), where his grandad, parents and four siblings had lived. Walking down a path, which was probably little-changed, and imagining his 19 year old grandad also walking down it for the last time to go to England, moved David to tears. Another, older cousin, was introduced when we visited her holiday home, a tiny cottage where she was born. So I should mention our trip to Letterkenny Civil Registry, where David got his Grandad's birth certificate, in order to apply for Irish citizenship!
Our big thanks for all the resources of this site and those who responded.