After World War II Grays were founder members of the Corinthian League, and were its inaugural champions and League Cup winners in 1945–46. They were league runners-up in 1951–52, and the following season saw them qualify for the first round of the FA Cup for the first time, losing 5–0 at home to Llanelli. They were league runners-up again in 1954–55 and 1956–57, before rejoining the Athenian League in 1958. When the league gained two more divisions in 1963, the club were placed in the Premier Division, where they remained until being relegated to Division One at the end of the 1971–72 season, in which they had finished bottom of the table. In 1977 the league was reorganised into a single division, and the club were runners-up in 1982–83.