Request help from our English friends in helping to find a missing bout for Jack O'Brien
8-20-1906 bout happened at Newcastle, ENGLAND(not Newcastle, PA as most records show).
American newspapers report he had TWO fights AT Newcastle, England
He left the states on 8-01-1906, then left England on 9-01-1906.
Allowing 13 or 14 days for ocean travel, that would put the days in England from 8-14-1906 to 9-01-1906.
Limit your search to these days. I would check 8-20-1906 first to see if he had two fights on the same day.
In my opinion, this would be a significant find.
Good luck.