After much more phone surfing, I found this posted on the MP museum website:
http://mpmuseum.org/provostbd.html
"Initially, all ranks were to wear the collar of the blouse closed, however it was not long before officers were permitted to wear the blouse collar open, showing a shirt collar and necktie. Blouse collars were often lined with battledress material or khaki cotton. Until late 1944, Other Ranks were not permitted to wear the collar open, even off duty."
and it did show a picture of a Staff Sgt's walking out dress tailored as such:
"Staff Sergeant's "Walking Out" Blouse, Canada, circa 1945. This is an example of a heavily tailored blouse. The lapels have been modified and lined with a fine serge material."
So now I am just wondering about the Artificer badge being sewn on instead of rank, and/or how many times did this guy do the hatless dance to stay a Pte after 4 years service with probably 3 of those overseas?