After World War I the club left the East Anglian League, but continued to play in the South Essex and Essex & Suffolk Border leagues. In 1921 they left the South Essex League, but the following year they joined the Middlesex League, winning it in their only season. In 1923–24 the club won the Border League, and a year later joined the Spartan League. In 1935 they were founder members of the Eastern Counties League. Two years later they left to establish the Essex County League. However, Town's poor performances in the ECL had convinced supporters that the club should turn professional like nearby Ipswich Town. Officials at the club were against the idea, resulting in a new professional club, Colchester United, being formed in March 1937, which would also play at Layer Road. United joined the Southern League and crowds at Town matches quickly dwindled. In December United formed a reserve team, signing many Town players. As a result of this and financial problems (the club were £300 in debt), they folded in the same month.