Flag of Cornwall, Ontario as granted by the Canadian Heraldic Authority. Not widely used as the city has their own version. It is for ceremonial purposes.
Own work
Modeled from:

http://flagspot.net/flags/ca-on-co.html
http://archive.gg.ca/heraldry/pub-reg/project.asp?lang=e&amp;ProjectID=540
Svgalbertian