Catherine was born in 1891, the daughter of fisherman Norman MacCuish and Rebecca MacCusbic of Backhill. When Catherine was 9 years old, her father obtained 19 Borve, one of the newly assigned crofts that replaced Borve Farm.

Catherine became a domestic servant, working for Murdo Morrison at the UFC manse in 1911. In 1929 she married Alexander MacKillop, with whom she was to have a son. They made their home at 19 Allotments, Pol an Oir, where they ran a shop.