Caption: CPR 4-6-2 class G3h engine 2459 leads a passenger train on Montreal Island on 28 August 1951.
Later colour images show it with grey boiler jacket and tuscan red tender side and below the running board.
Based on data for sister CP 2461, probably built by CLC Kingston in March or April 1945.

Quoting from R.L. Kennedy's website "Old Time Trains":
These "Twenty Four Hundreds" (actually, 2351-2472) were very capable locomotives built with one piece cast bed and multiple throttle. They were as different as day and night compared to earlier G3's 2300- 2350.
They were considered the best steam locomotive on the CPR, true dual service freight or passenger engines with 75 inch diameter drivers. They were the only class painted in either freight black and/or passenger tuscan red.

I believe that this is a westbound afternoon train from Windsor Station approaching Montreal West station. One of the low-rise residential buildings cropped off at right had "Westhaven Village" on it, as if to advertise.
Westhaven Elmhurst Community Rec Associaton maps nearby, and very similar buildings can be found here in streetviews.
Signal M44 is gone, but "42" signals are on a signal bridge a bit further east. (CP Westmount Sub MP 4.2)