Lewes then left the Mid-Sussex League for a reformed East Sussex League, and were runners-up in 1912–13. Although they finished bottom of the East Sussex League the following season, the club also played in the Mid-Sussex League and won the league title. After World War I they spent the 1919–20 season in the Brighton, Hove & District League. In 1920 they were founder members of the Sussex County League. The club were runners-up in 1924–25 and again in 1933–34 and 1958–59, also winning the League Cup in 1938–39.