For the period 1845–99, statistical data are available to examine the spread of underdraining in England as a whole. The loan capital that was established from 1840 onwards by the body of land-improvement legislation provided landowners with an alternative source to private funds for financing underdraining. From 1847 to 1899, under this legislation, representing the public component of draining activity, £8,995,000 was lent for the purpose of underdraining in England, Scotland and Wales. The records of these loans have in the main survived and may be used to construct an index of the amount and distribution of land drained in England over the period. Although the political and administrative framework of this landimprovement legislation has been described by F. M. L. Thompson and D. Spring, a review of its development is essential for an understanding of the nature and value of this data source on underdraining in the second half of the nineteenth century.

The development of government- and improvement-company-financed draining

The various land improvement acts arose from efforts to overcome the limitations that contemporaries perceived were placed on owners of settled estates in undertaking agricultural improvement. Although the extent of settled estates and the effect of settlement on agricultural improvement remain unclear, a series of acts was passed from 1840 onwards which aimed at relieving the restrictions supposedly experienced on settled estates by allowing tenants for life to borrow money for agricultural improvement and to establish a rentcharge on the lands improved to redeem the capital and interest over a number of years. Although eventually applied to a range of improvements, underdraining was the first and most important of the improvements that these acts permitted.