By the start of World War II, Risso was a foreman mechanic and a City Council employee. When most of Gibraltar's civilian population was evacuated, Risso was one of the few Gibraltarians that remained on The Rock. In September 1942, a group of fellow Gibraltarians, clerks and workers, led by Risso came together to form the AACR, an association advocating the Gibraltarians' civil rights. Risso was president of the AACR from 1942 to 1948, when he was succeeded by former vicepresident, Joshua Hassan. In 1947, he was appointed president of the Gibraltar Confederation of Labour, a trade union created to represent the AACR's working class supporters.