Hi Chris
You're right, it is amazing the way one person's odd bit of information turns out to be what someone else was looking for!
I learned from Toronto City Archives that the house was built in 1912, which puts the pictures later than my guess of 1910.
The Archives supplied a list of occupants up to 1918, and I've since looked at online street directories up to 1921 without encountering any familiar names. It's quite possible that the people in the photo are just friends of my grandfather and not related at all.
If it turned out to have been taken late enough to be your relatives, then the fact James was from Sunderland would make me pretty sure that they were people my grandfather, Robert Gray, an engineering foreman, knew when he worked in Stockton on Tees and/or Darlington. He moved back to Scotland about 1910.
The two photos are very similar. I've put them in Dropbox if you would like to download copies.
https://dl.dropbox.com/u/5168710/Toronto-House-1.jpghttps://dl.dropbox.com/u/5168710/Toronto-house-2.jpgIsabel