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. On that trip Lion entertained the President of the United States-President Franklin D. Roosevelt at the Waldorf Astoria in New York. This was a distinction that no other calypsonian had at that time. When Lion was asked by President Roosevelt where he & Atilla were from, Lion responded “The Land of Calypso” a name which Trinidad is still known by. Roaring Lion achieved fame for his linguistic prowess as much as for his catchy tunes. His lyrics, delivered in rapid-fire style, show an impeccable command of the English language (as well as Trinidadian English Creole), and are replete with witty turns of phrase, humorous metaphors, and clever alliteration and internal rhymes. Of all the early calypsonians, he was by far the most scandalous, with the most banned songs by a large margin. His "Netty Netty", the song of a prostitute who left town to have an abortion operation, shocked not only Trinidad and Tobago, but also neighbouring countries such as Grenada, where he was banned for a while (as his song "Excursion to Grenada" relates).