It turned senior in 1881 by joining the Scottish Football Association under the name Southern.

At that stage the club was drawn at Morton and lost 5–0, a turning point having a goal disallowed for a prior foul when 3–0 down.

[4] It first entered the Renfrewshire Cup in 1882–83, and that year was its best run, reaching the quarter-finals; however that was after one win and one bye.

In the Scottish Cup it lost 10–1 at home to Neilston; an early indication of the erosion in the team's resources being that Southern only had ten men.

[13] In 1884 it moved to Berrylands Park, a 2-minute walk from Upper Greenock railway station.