From a young age, Roaring Lion (de Leon's adopted stage name) became known for his skill in creating calypsos (particularly in his ability to extemporize lyrics on any subject). Contrary to his humble origins, he cultivated a refined stage persona and always appeared sharply dressed. His career officially began in 1924; he cut his first sides in his late teens. He recorded extensively between the 1930s and 1950s, and was one of the calypsonians who deserves the most credit for the increasing international popularity of the genre during this period. In March 1934 the Trinidadian phonograph merchant Eduardo Sa Gomes sent Roaring Lion and Attila The Hun to New York to record; they became the first calypsonians to record abroad. He was also the only calypsonian vocalist of his generation who could read and write musical notation.