My ancestors on my mothers side were millers in Loddiswell, Devon.
When my 2x great grandfather came to Canada he found work right away at one of the mills in Montreal.
I wonder if perhaps he worked at the Montreal Glenora (Ogilvie) Flour Mill in August 1874 when there was a fire - one of many fires that broke out in flour mills.
In doing some research I came across some info and lists of mills.
Database of Mills
Directory of the milling industry in Canada: containing alphabetical lists of flour mills, cereal mills, grist mills, and chopping mills, indexed as to provinces, towns 1915
Report of the Board of commissioners of the first Millers' international exhibition, held in Cincinnati, 1881
About Canadian wheat facts and figures : with a directory of millers, shippers and buyers of flour, grain and produce, 1899