This information is not held centrally. To collate this information would involve contacting every closed establishment in order to identify how many prisoners are currently on each local escape list. This would incur a disproportionate cost.
All closed prisons are required to have in place a system to identify and manage prisoners who are placed on the escape list. A prisoner may be placed on the escape list if they pose a current and significant threat of escaping that cannot be addressed through normal security arrangements.