gangmaster
From Longman Dictionary of Contemporary Englishgangmastergang‧mas‧ter /ˈɡæŋˌmɑːstə $ -ˌmæstər/ noun [countable] British English someone who is in charge of a large group of foreign labourers (=people who work outdoors, using their physical strength), especially labourers who do not have official permission to work in Britain