No room or cell shall be used as sleeping accommodation for a prisoner unless it has been certified in the manner required by section 14 of the Prison Act 1952 in the case of a cell used for the confinement of a prisoner.

A certificate given under that section or this rule shall specify the maximum number of prisoners who may sleep or be confined at one time in the room or cell to which it relates, and the number so specified shall not be exceeded without the leave of the Secretary of State.