Mary Campbell was the daughter of Norman Campbell and Marion Morrison. Born in 1836, she lived on Pabbay until 1850, when her father obtained croft 6a Ruisgarry on the island of Berneray. However, the croft was taken for the Glebe in 1854 and the family became cottars at Quay.

Following her parents' death, Mary continued to live at Quay with her sister Effie. When Effie married Murdo Campbell from Molinginish and settled there, Mary moved there too. She never married.