I’ve downloaded and adjusted the images on my PC and attached them to this response.
Except that it looks like a park, there’s nothing of substance I can identify in the background of the picture. The three men are wearing the Canadian variation of the British Army’s Service Dress (SD) uniform that was worn from 1907.
The identified differences being the 7 tunic closure buttons (British had 5) and the conventional tunic collar (all stand and no fall), whereas British tunic had the Prussian style (stand and fall) collar.
The Canadian other ranks uniforms didn’t stand up well to service in France and many were replaced with British tunics. I’m not sure if the Canadian variation was commonly issued post WWI or if they used the British pattern, but the British version was issued up to 1939 when it was replaced with the short tunic battle dress.
It’s possible the photograph was taken in Canada pre WWI, but whatever the period it was and if you can identify possible names, you should find some record at http://www.collectionscanada.gc.ca/genealogy/022-909.006-e.h...
He’s wearing the British & Canadian Army’s battle dress (Australia had a different uniform) issued from 1939; unfortunately his shoulder titles and flash are not clear enough to identify anything else.
The battle dress was worn until the 1950’s but looking at the background of this studio picture I would place it nearer WW2 rather than later.