Hi Ticker,
There were a number of the "Pals" units, I have not seen anything on the Scarborough one unfortunately.
There are a number of references to Accrington, Sheffield, Leeds etc, perhaps you could try the Imperial War Museum as they have a number of sources.
I think the idea of the "Pals" was that they were usually men that knew each other so there was already a sense of comradeship which would be of benefit in the circumstances they would face.
It was not confined to big towns, in many villages men signed up together and as our memorials show died together, an appropriate subject for today!
Sorry only to provide only general info.
What a superb photo to have of your ancestors.
Trangy