Matt Merrigan was a member of the small Irish Trotskyist group in the 1940s, the Revolutionary Socialist Party, and a socialist all his life. He eventually became president of the Irish Congress of Trade Unions, and died in 2000.
In the mid-50s, for a while, he wrote reports on Ireland for Labor Action, the paper of the Independent Socialist League of Max Shachtman, Hal Draper, and others in the USA.