In 1971 the Greater London League merged with the Metropolitan League to form the Metropolitan–London League, with Canvey Island placed in Division One. When the league merged with the Spartan League in 1975 they joined the Essex Senior League. They were runners-up in 1978–79 and won the League Cup the following season. They won the league for the first time in 1986–87. After winning the league and League Cup again under Jeff King in 1992–93, a season which also saw the club reach the semi-finals of the FA Vase, they moved up to Division Three of the Isthmian League in 1994. Their first season in Division Three saw them finish as runners-up, earning promotion to Division Two. The club went on to win Division Two the following season, resulting in promotion to Division One. They also reached the first round of the FA Cup for the first time, eventually losing 4–1 to Brighton in a replay.