That must be the Canadian equivalent of the US "515" which is from 1955. Here is a pic of my 515 with all the original accessories. The bag on mine in the picture is from a later model. I have the original bag which matches the one on your machine but mine is in fragile condition.
Didn't Hoover do the same thing with their model numbers depending upon where they were manufactured? Your UK-made Hoover 612 for instance would be the US model 61.