Since about the last third of the nineteenth century, the casual labour question has been the major problem of dock labour. Well into the middle of the twentieth century, many ports offered their workers only unstable and unpredictable job opportunities. Sea and weather conditions, business cycles and harvest times of crops such as grain, cotton and fruit all contributed to the irregularity of ship arrivals, and hence unstable employment. Even today the port transport industry has no entirely continuous flow of traffic. Apart from this fluctuating demand for labour, the casual dock labour market was characterised by two important features: first, the casuals were only engaged for a few days and then dismissed; and second, there was a great surplus of labour. 1 The great number of men employed in the ports intensified these problems. In the 1920s, for example, the great ports of the world often employed a daily average of tens of thousands of workers: Shanghai 60,000 (1920s), London 54,558 (1925), New York c. 50,000 (end of 1920s), Hamburg 21,000 (1925), Liverpool 20,580 (1925). 2