It is arranged by present day district boundaries. The Local Government Act 1858 and successors enabled local authorities to make bye-laws to control buildings and streets. Plans for new buildings, or for extensions to existing property, had to be submitted to the authority for approval before work could commence. Prior to this, local private acts were the only way to enforce control on building development.
Building control concerns property developments and alterations.
Plans therefore include property built before the 1850s if structural alterations have been made since the advent of building control. Only structural work is recorded and not, for example, area water, gas and electricity supply. Boundaries are approximate. The vendors or estate plans often show the layout of building plots in an area. The plot numbers on plans frequently coincide with the plot numbers on building control plans and are a useful reference for the property in a wider context.