The John Backhouse Mill
John Backhouse emigrated from Yorkshire to the United States in 1791 but shortly thereafter, moved to Upper Canada. He served as a Major of the 1st Norfolk Militia in the War of 1812 and became a chairman of the Quarter Sessions, then the chief instrument of local government. He is believed to have erected this mill 1798. It remained in the possession of his descendants until its purchase 1955 by the Big Creek Region Conservation Authority having been in continuous operation for a longer period than any mill in this province.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.