In Britain, section 7 of the Ministry of Munitions Act prevented workers from transferring freely from one job to another by requiring workmen to obtain a leaving certifi cate before engaging in alternative employment. Th is harsh provision had a twofold motive. First, the depletion of the reserve army of labor gave workers enhanced bargaining power, which forced employers to bid up wages in order to attract available labor, especially skilled labor. By imposing a political limit on such mobility, the government could ensure a cap on wages. Second, these certifi cates also prevented the constant turnover of labor, which hampered the production process.

Clara E. Mattei, The Capital Order, loc. 176