Gartree opened in 1965 as a category C training prison but quickly changed its role and came within the high security system, reverting to a category B prison in 1992. Since then the population of indeterminate sentenced prisoners has been growing and in 1997 its role changed to that of a main lifer centre and is the largest lifer centre in the UK.
HMP Gartree is run by HMPS, and is part of the East Midlands group of prisons. There are six main residential units. Wings A – D are the original 1960s build, although all have been refurbished since opening. Wings G and H are newer build units and have been open since 2005/06. All the residential units are generic units with no specific function or dedicated role and all are single cells. There is also a 12-bed segregation unit. A new outpatient health care clinic centre was opened in 2010. The Gartree therapeutic community (GTC) for up to 24 prisoners offers extensive TC intervention work. F1 comprises 12 cells and is run as a designated unit for prisoners who have learning difficulties or personality disorders and require additional assistance and guidance.
All the prisoners are in single cells after spending induction period in double cells and the capacity of the prison is 719. The prison is unique in having 2 #1 governors who share the role and they are Alexandra Barker and Michael Wood, in post since October 2016.