Smithsonian Folkways Biography-
http://www.folkways.si.edu/explore_folkways/lord_invader.aspx

No personal comments other than he was born Dec. 14, 1914, grew up around San Fernando, and began improvising calypsos at a young age.
Labeled 'a country boy by fellow Trinidadians. His tailor gave Grant his moniker "so when you go up to the city you be invadin' the capital."
This reference to a tailor may suggest that Grant's family was not one that required the young man to have another job.