Since most labourers' work came from farming it is important to attempt to try to estimate how much demand there was for agricultural labour and how it changed over time. Labourers could only have worked more days, or increased the intensity of their work, if the demand for work was there. The earnings worked out in the last chapter represent fairly full employment, but many day labourers appear in account books working fewer days. Of course they might have been working on their own farms or moving between farms as labour was needed, but this cannot be reconstructed from accounts. However, a global estimate of demand for labour can be made by estimating the number of days of labour required per acre to produce crops and animal products, and then multiplying this by estimates of the number of acres devoted to pastoral and arable farming in England, as was done earlier for women.