Years ago, in a distant library, I regularly ran a photo identification workshop. Photos like this group shot of English women would show up with the question, “When was this photo taken? The woman third from the left on the front row looks like my great great Aunt Lizzie or Aunt Edna. Can you help?”
HOW WOULD YOU SOLVE THIS PROBLEM?
Genealogy Education 
In a group shot or a portrait, look for the youngest adult female. Her clothing is likely to be the most fashionable and can be dated. Milliners stayed in business by changing hat styles annually, so they too can be considered. Remember hats are cheaper than good dresses. many women used the same dated dress from a year or two ago, but with a hat from the current show window of the milliner.
Of course there are always those women whose circumstances prevent them from buying new things. I once found a series of family photos of a growing family in the west. In three photos about 2 years apart the tired mother was wearing the same dress she wore as a new bride. As her family grew, she and her husband looked increasingly worn. A graphic tale of struggle on the farming frontier.
Ken
Interesting picture!
I strongly agree with your comments about thinking of long worn or ‘hand me down’ clothing when looking at photograph identification…sisters or close cousins or neighbours might be seen in the same outfits (or parts of them) at different times. If you know the area where the photo may have been taken in, have a look at contemporary catalogues, magazines & newspapers for fashion news & sewing patterns. Not everyone could patronize the local milliner. They might redo a dress or hat to suit the newest trend.
This photo though has lots more clues, I think.
Briefly, even if there is no other info associated with it—
1. It appears to have a photographer’s # on it—if you know the area it might have been taken in, does an archives or museum have a copy of this picture or similar pictures —same setting or even same type of # series/handwriting?
2. There is one older woman in a group of younger looking women of various ages—might she be a teacher of some kind & this a reunion or her retirement or a special birthday?
3. The room has electric lights—this may help with dating.
4. Looks as if there are benches in the room that have been moved aside for the group photo—possibly a school or church meeting room setting?
5. Back to clothes-almost every woman has a coat on—one in the front row has a muff. Was the photo taken in early fall or winter?
6. Is that a railing in the background? Maybe this is a choir loft or stage area?
7. Can any details be seen if the photo is blown up a bit—some of the women seem to be wearing ribbons or badges; the older woman, for example.
The older woman could be a special guest or out of town speaker.
Once you have gathered some info from the picture & given it a tentative date, make up a timeline for great great Aunt Lizzie or Aunt Edna. If you think that picture was taken in 1911, how old would they have been then & what do you know about where they were in 1911 (there’s the census, for instance, if this is in Canada) & what do you know about what they were doing or about their past. Did either attend a girls school or were they active in a church choir or the W.C.T.U or a women’s suffrage association! Would a local paper have mentioned them travelling or attending a special event?