HMP Erlestoke was built on the former grounds of Erlestoke Manor House. The site was taken over 50 years ago as a detention centre and in1977 it became a young prisoners centre. The prison re-roled in 1988 as a category C adult male training prison and life-sentenced prisoners were first received in the 1990s. It has a focus on the rehabilitation of a longer-term population and is a national resource for high-intensity programmes on domestic violence, alcohol-related violence and substance abuse. HMP Erlestoke is run by HMPS as part of the South West Region. It has a capacity of 494 and the #1 governor is Tim Knight who has been in charge since July 2016
- Alfred – 64-bed unit, 58 single cells and three double cells.
- Imber – progression regime, 40 single cells.
- Marlborough – drug rehabilitation unit, up to 60 prisoners in 30 double cells.
- Sarum – 54-bed enhanced unit, 50 single cells and two double cells
- Silbury A – downstairs – progression regime/social care, 28 single cells and two adapted cells.
- Silbury A – upstairs – super enhanced unit, 34 single cells.
- Silbury B – first night/induction, 30 double cells and 30 single cells.
- Wessex – 66-bed unit, 58 single cells and four double cells.
- Wren – 24-bed super enhanced unit, all single cells.
- Care and separation unit – eight cells for segregated prisoners, two orderly cells, one special accommodation cell and one constant supervision cell.