The BBS was the principal union involved in the 1971 Harco work-in, in which rank-and-file workers seized control of a heavy engineering factory in the Sydney suburb of Campbelltown to protest the sacking of five boilermakers. The workers, inspired by the example of 'work-ins' at Upper Clyde Shipbuilders in the UK and French car workers during the May 68 of 1968, occupied the factory for a period of four weeks.