Directors of offender management must ensure that each cell used for the confinement of prisoners has sufficient heating, lighting and ventilation and is of adequate size for the number or prisoners it is approved for. Each such cell is recorded on a prison’s cell certificate.
Not all accommodation recorded on a prison’s cell certificate is part of its certified normal accommodation and in the vast majority of cases will also not form part of its operational capacity. This is due to a range of operational reasons, which include those cells that are part of segregation units (where prisoners should only be held under a governor’s express authority), cells in in-patient health care centres (which are only suitable for prisoners with relevant health needs) and holding cells in prison receptions (which are not suitable for holding prisoners overnight).
As of 14 December 2009, based on information from central records, about 2,712 places were not included in the certified normal accommodation (or uncrowded capacity) of the prison estate. This equates to an average of 19 cells per prison.
These figures have been drawn from central administrative/recording systems, which, as with any large scale recording system, are subject to possible errors with data entry and processing.