Based on payroll data of blue-collar male workers in the UK’s engineering and metal working industries between the mid-1920s and mid-1960s, this paper investigates piecework-timework pay differentials through time. The period covers several pre-Depression years, the Great Depression, the run up to WW2, the war itself, and the post war period. A major widening of the differentials occurred during the late 1920s and during the run-up to and the expansion of WW2 activities. In contrast, the Depression and the post-war years witnessed considerable narrowing of the differentials. Associated labour market topics include pieceworkers’ compensating pay differentials and the transaction costs of pricing piecework output. The surge in women’s employment in engineering and metal working in the early war years is shown to have contributed to changes in the male differentials.