As I see your source was the Madawaska records and they seem to have been compiled from memory. A while back I sent for a copy of the marriage record from Kamouraska and on it it states that Thomas Mathers was a [navigateur] seaman from Liverpool England and he was the eldest son of Samuel Mathers and Elizabeth McMinne. McDunn is the name that followed to Madawaska and was remembered incorrectly. My research has not been fruitful in Liverpool because it was the point of departure for many from Great Britain. I sinserely hope that this helps you and that you will post future findings because many of us from New Brunswick are from this line.