In what year was the team founded that won the 1956-1957 Irish League championship?
1956–57 Irish League The Irish League in season 1956–57 comprised 12 teams, and Glenavon won the championship.
Peamount United F.C. Peamount United Football Club (Irish: "Club Sacair Mullaigh na Pise" ) is an Irish association football club based in Newcastle, South Dublin. The club is best known for its senior women's team who in 2011–12 became founder members and inaugural champions of the Women's National League. They have also represented the Republic of Ireland in Europe and in 2011–12 they became the first Republic of Ireland team, including men's team, to qualify from their group for the knockout stages of a European competition. The club's senior men's team compete in the Leinster Senior League. Peamount United also field teams in the Dublin Women's Soccer League, the Dublin and District Schoolboys League and the Metropolitan Girls League.