Hello. As far as I know that mark has not been identified.
However, I do have an idea.
In one of my older Canadian books it mentions on one page the Ontario Silver Company.
Founded in 1883 in Thorold, Ontario, Canada. Moved to Niagra Falls in 1900.
Around 1904 or 1905 the firm was taken over by the Wm. Rogers Mfg. Company.
At the bottom of the page it has two pictures of marks.
One pictures reads Ontario Silver Co. A1. The other Victoria Silver O.S. (Ontario Silver) Co.
Victoria Silver could be a trademark of theirs or just the name of the pattern, I'm not sure.
Pat.