The Government Says

Guidance: Treatment of unconvicted, unsentenced and civil prisoners: PSO 4600

Guidance: Treatment of unconvicted, unsentenced and civil prisoners: PSO 4600
Local copy of pso-4600-unconvicted-unsentenced-civil-prisoners.pdf

https://www.gov.uk/government/publications/treatment-of-unconvicted-unsentenced-and-civil-prisoners-pso-4600

seen at 03:31, 14 May in Ministry of Justice - Activity on GOV.UK.