Aileen,
Seamus O'Connor was the eldest of ten children born to Thomas and Sara (nee Reilly). He was born in 1882, Newton House, St. Margaret's Nth, Co. Dublin and died in 1960, Howth Road, Dublin 3.
When my grandmother and her cousins stayed with him on 7 Hollybrook Road, Dublin, in 1947 Seamus was the Sheriff of Dublin. My grandmother's letter dated July 25, 1947 said he was attending a garden party with De Valera. Other letters shared the day to day life in Dublin at the time (post-war), strikes and much more. Our cousin, Marie, traced the family back to 1771 and presented the book to family member attending a reunion in 2000. I did not know about the reunion or I would have been there. Marie shared a copy of the book with me. I've added more information and made corrections to the information (as was intended by Marie). Do you want the names of Seamus' sisters and brothers? I don't have information on His father's family but David probably does (dabirchall). I have the history of the O'Reilly family. Hope some of this helps.
Mattie Mae