I heard this last week from one of the workers who had occupied the Enfield Visteon factory in April. He used it when referring to the role of Unite, the union at the plant, in alerting management to a challenge on the question of pensions.
This doesn't feature in W.G. Smith, The Oxford Dictionary of English Proverbs, ed. F.P. Wilson, 3rd edn (Oxford: Oxford University Press, 1970).