Warren Hill opened in 1982 to accommodate Cat C Young Offenders in a closed environment. It was part of Hollesley Bay Colony, the other part of the prison being an open Youth Custody Centre/Detention Centre.
When the CJ Act of 1991 came into force the population of open Young Offenders dwindled, and in 1992 the open establishment was adapted to accommodate adult category Ds – initially as a minority but the adult population was the majority within the open prison, with Young Offenders occupying one unit.
In April 2002 though retaining some shared services, HMP & YOI Hollesley Bay became two separate prisons. The Open complex retained the name Hollesley Bay and the Juvenile parts (Warren Hill and the Carlford Unit) became HMP & YOI Warren Hill.
HMP Warren Hill now holds Indeterminate sentenced Cat C Male Prisoners, who cannot move to open conditions working to a Progression Regime. In April 2016, work will begin on planning the merge of HMP Warren Hill with HMP & YOI Hollesley Bay, which is due to take place in October 2016.
Grove Road, Hollesley, Woodbridge IP12 3BF