There is a lot of documentation about the battle at www.battleofprestonpans1745.org

The images of the area in this document are good:
http://www.battleofprestonpans1745.org/heritagetrust/html/heritage_campaign.pdf

It seems that the place might have been in an industrial slump at the time of the attack. The salt industry had collapsed and the pottery hadn't yet got under way, nor was brewing yet on the scale it got to later. That left mining, fishing and farming as the basis of the economy. Neither colliers nor fishermen could have been expected to have any sympathy with the invaders. Colliers were serfs and seem to have had no sense of national or ideological identity whatever - their world ended at the parish boundary, they couldn't leave it, and they had essentially no religion (the Kirk had only a token presence in mining communities, and the Episcopalianism of the Stuarts would have been as alien as Shinto). The fisherfolk were the exact opposite, with an internationalist coastal community that linked Scotland, England and the Netherlands, and with an intense fundamentalist Protestantism that has persisted to the present day. Farmworkers had no choice but to align themselves with whichever side their laird backed, which in East Lothian was mostly the Government.

With the Jacobite leadership sharing the sort of attitudes Sandy Maclean is displaying here, all were simply massacre fodder, just as they became for the Government in 1797.