Wow. You all are wonderfully skilled. I believe we can now, unequivocally, say this is a photo of who we believed it to be.
jim1: The reason I was a bit disappointed with the late WWI period is that the young woman we believed this to be emigrated to the US in early 1911. Her father and an older brother had emigrated the year before so, perhaps, this photo could have been intended either for her absent family members or, possibly for a beau she knew she might never see again.
LittleNell: Where did you find the directory information? It does look like the company was on Argyle Street in 1910/early 1911. Certainly close enough to the period you found and I would like to use your source to research other establishments that are/may be related to my ancestors (John Cairns, Bootmaker in Johnstone and Cairns Marmalade in Paisley) to see what became of those businesses.
IgorStrav: Spot on. This girl was born Jan 27, 1891.
Thanks to all of you.