Prisoners sentenced in England and Wales cannot, as a matter of course, be held in Scottish prisons due to the differing legal jurisdictions.
The number of police cells made available under Operation Safeguard is at the discretion of Chief Constables who take their operational needs into account.
There are up to 400 places available in police cells in England and Wales under Operation Safeguard.
The number of prisoners held in police cells varies on a daily basis and is dependent on court activity and the management of regional prison population pressures.