Campbell's of Londonderry

[Gadget]

Agree with Wiggy and Carol - possibly 1907-11, from hairstyles and clothing.

Also, it's a very odd grouping if it was a graduation. Wouldn't she be in the centre of the picture, rather than at the end?

Gadget

[Wiggy]

My thought too re grouping.

Also she looks too young to have been born in 1868.

[Gadget]

It looks more like a celebration of something to do with the middle couple - anniversary, wedding, etc. - but why would she be wearing academic dress?  Could it be that she wasn't there and has been added from another photo 

[Treetotal]

I agree with the comments made, but, I'm not convinced that she is wearing a cap and gown 
Carol

[Wiggy]

I agree with the comments made, but, I'm not convinced that she is wearing a cap and gown 
Carol

Nor am I!

Wiggy

[Gadget]

I'm not either - it's definitely not a graduation photo.

Maybe the OP has relatives, who were married/had an anniversary/other around the approx dates we've given.

[daisy3]

Apologies for not replying sooner but have been doing a lot of digging, first let me say thank you to all who responded, and have come to the conclusion that you are correct, I think the young lady is now Minnie's younger sister Gertrude,born 1885, the young couple is very likely their older sisters wedding, 1900, the older lady far right is definitely my gr8 grandmother Mary CAMPBELL. I still believe that Gertrude is wearing some kind of cap and gown, going by the enhanced photo, why I don't know. Some background, Gertrude was killed in a car accident in America when she was in her 20s, the bride, Christina died four years after this photo was taken, and Mary CAMPBELL raised her two very young children to adulthood, quite a sad story.
I am still working on the rest of the group, but thank you everyone for your help.

Regards Daisy

[Wiggy]

Good to hear you've done more digging Daisy.  Sounds as if your digging has brought you closer to the date of the photo, and the subject of the photo.

Is there any chance of a better scan?  If so we could pick up more detail.    See the thread about scanning at the top of the photo board.     

Wiggy   

[Wiggy]

Have you any likely weddings - or other celebrations - some years later Daisy.   Another 6-10 years later maybe?      .  1900 still seems a bit early for the fashions being worn.

Wiggy.