Frontline International were a late 70's and 80's Sound System from Brixton, London. The sound was owned by Trevor Frontline AKA Half Caste (a joke due to his dark skin). Lesley Lyrics is quoted as seeing them with MC's Colonel Flux and Welton Youth in 1978(1). Circa 1980 the crew featured selector Natty (formerly of Sir Coxsone) and MC's Chukie and General Saint by the mid 80's the selector was Shortman and the main MC's Bobby Joe & Lieutenant Lecture Lyrics.

They had a Sunday night residency at Studio 200 in Balham, South London in 1980.

(1) http://www.ligali.org/article.php?id=587 (original link doesn't work but here is a cached one)