The British government began publishing large collections of prison statistics in 1818. A specific schedule for a (statistical) return, set out in tabular form, was included in An Act to procure Returns of Persons committed, tried, and convicted for Criminal Offenses and Misdemeanors, 55 Geo. III c. 49 (12 May 1815). This act required returns to be sent to the Home Department every year within the first fourteen days of January. The first published collection of returns in this form was for 1818. An expanded schedule, also set out in tabular form, was included in An Act for consolidating and amending the Laws relating to the building, repairing and regulating of certain Gaols and House of Correction in England and Wales, 4 George IV, c. 64 (10 July 1823).
The scholarly literature has discounted the value of these early prison statistics. A major work on English prisons noted:
Even the number of prisons is uncertain: whereas in 1812 James Neild reported that there were 317 prisons in England and Wales, and in 1818 the Society for the Improvement of Prison Discipline counted a total of 518 for the whole of the United Kingdom, parliamentary returns for England and Wales gave 335 and 291 in 1819 and 1833 respectively.^ ^
The Society for the Improvement of Prison Discipline’s count for 1818 is from its Fifth Report (1823) and is based on parliamentary returns.^ Prisons often have a compound description, such as “common gaol and house of correction.” The rule for counting such prisons (whether as one or two prisons) would greatly affect the total count. Small detention cells for temporary detention also greatly affect the total prison count, but such prisons have little effect on the average number of persons in prison during the year. A reasonably consistent count of prisons holding at least one prisoner by county can be constructed from 1780.
English and Wales prison statistics are among the best early national statistics other than general population statistics. Useful estimates for the average prisoner population exist from 1670. Good yearly data on the average number of prisoners are available from 1836.