Long ago, before liberalisation and globalisation gave it a standard, happy, upmarket gloss, Hindi cinema also boasted of a series of films that introduced my generation to the ideas of class struggle, workers' rights and unions. They spoke about the exploitation of the innocent villager/worker, usually forced to migrate to a town from his village, in search of a job at a mill, mine or construction site. This Labour Day I revisit 10 such classics.