Thanks Carol and Caroline. I'm starting to believe that they are Maxwell Drennan b: 1877 and his wife Sarah Jane McAlistair m: 30 Aug 1901 Antrim, with their son William Alexander Drennan b: 1903. They emigrated to California in 1907. The boy shows in two other photos; in a group with mother and three sisters, with the right family mix and ages, and one in a badly trimmed down picture, on his own, aged about six, on the back of which is written: To Mrs Minnie ........ From Wm A........, the dots showing the missing parts. The only Minnie in the wider Drennan family of this time was a Minnie Pearl Kaulbach, married to Maxwell's brother who had emigrated to Nova Scotia! Whilst I'm tempted to say "elementary my dear Watson" I'm wondering why my Drennan grandfather would have had this last photo in his possession.
Ward