HMP Grendon

A therapeutic community prison

In shortGrendon opened in 1962 and is a therapeutic community prison whose sole purpose is therapy.

• Opened1962In Buckinghamshire
• Operational capacity (combined)546489 held at 24 August 2026; one figure for Grendon and HMP Spring Hill
• Grendon’s own capacity233As given by HMPPS’s recruitment page

HMP Grendon in Buckinghamshire opened in 1962. HM Inspectorate of Prisons (HMIP) says it was initially an experimental psychiatric prison for prisoners with antisocial personality disorders and developed into a series of discrete therapeutic communities, one of which is for a specific group of prisoners.

HMIP adds that Grendon has been one of the most researched forensic establishments in the world, and that studies have shown lower levels of reoffending for men who stay longer than 18 months. See our categories guide for how a category B training prison differs from a standard one.

TC plus (2014)

A unit for prisoners with learning disabilities opened in 2014, complementing similar provision at HMPs Dovegate and Gartree.

Democratic TC (IMB)

The IMB calls it the UK’s only therapeutic community (TC) prison whose sole purpose is therapy, in which prisoners take an active part, for example by chairing community meetings held twice weekly.

OPD pathway

Grendon is part of the national offender personality disorder (OPD) programme.

Joint management

Grendon and the adjacent open prison, HMP Spring Hill, are managed jointly by a single senior management team, so HMPPS publishes one combined capacity figure.

How the wings work and who is held

In shortFive therapeutic wings plus an assessment unit, holding mostly men on indeterminate sentences who normally move on to other prisons.

At the May 2023 inspection HMIP counted 171 prisoners, of whom 116 were serving indeterminate sentences and 54 determinate sentences, with six foreign nationals and 20% from black and minority ethnic backgrounds.

About 70 prisoners transferred in each year, and only five to 10 were released into the community annually, since men normally move on to other prisons.

The prison had an operational capacity of 188 then, a figure the IMB says has since risen to 236 following the reopening of a wing. The IMB notes there is no segregation unit.

A, B, C and D wings

Therapeutic communities of 40 to 45 beds (B wing was closed for fire improvement work in 2023).

F wing

A 20-bed TC plus unit for men with mild learning disabilities.

G wing

A 40-bed assessment and induction unit where, per the IMB, arriving men stay for three to six months.

Who leads each community

A custodial manager, a psychologist and a therapy manager, and staffed by Band 4 specialist officers and non-operational facilitators, according to HMIP.

Providers (HMIP 2023)

Practice Plus Group and Oxford Health NHS Foundation Trust for health care, Midlands Partnership NHS Foundation Trust for substance use treatment and Milton Keynes College for education.

• Literacy and numeracy lessons
• Vocational training
• On-site work such as food preparation and catering, maintenance and peer support (per the recruitment page)

What inspectors found in May 2023

In shortOne of the safest jails in the country, but with cells lacking toilets and a narrow curriculum.

• SafetyGood
• RespectGood
• Rehabilitation and release planningGood
• Purposeful activityNot sufficiently goodDown from ‘good’ in 2017

HMIP inspected from 2 to 19 May 2023 and published the report in August 2023. The Chief Inspector called Grendon ‘a unique, pioneering jail’ and said it was one of the safest in the country, with assaults and use of force very rare.

Discipline was maintained not through traditional adjudications but through standards set by prisoners and staff in democratic meetings, and relationships between staff and prisoners were excellent. Ofsted rated overall effectiveness as ‘requires improvement’.

Specialist officers and staffing

In shortTherapy depends on specially selected Band 4 officers, and 10 of those posts were vacant at the end of 2025.

• Band 4 vacancies10Specialist officers, at the end of 2025 (IMB)
• HMPPS 2025/26 rating91.7%‘Outstanding performance’ (rating 4 of 4)
• Officers in post129 FTEBand 3 to 5 officers against a target of 154, 25 below target at 30 June 2026 (Spring Hill is not listed separately)

Staff are central to what Grendon does, and HMIP is specific about them. It says the band 4 specialist prison officers were specially selected, had comprehensive training for their role and were well supported with regular clinical supervision and group sensitivity meetings to address the emotional demands of working in a therapeutic environment.

Leaders had developed succession pathways to address shortfalls, including training band 3 prison officers to fill the specialist role. Arrangements for clinical supervision and peer support, including careful managerial oversight and access to independent counselling for staff, were listed as notable positive practice.

• The IMB’s report for calendar year 2025, published in May 2026, shows how much therapy depends on those staff.
• Staff vacancies, particularly among Band 4 officers, were an issue, made worse by the staffing required for a reopened D wing.
• Men told monitors that cancelled or postponed therapy sessions affected their progress. Faith provision was also weakened.
• One of the IMB’s questions to the governor is whether there are new strategies for recruiting Band 4 officers.

Working here: pay, benefits and getting there

In shortNational pay zone with a £1,500 a year Band 3 supplement (3 October 2026) and a rural site where you will need to plan your travel.

• Earnings range£36,428 to £40,834Including the supplement, for 37 to 41 contracted hours (HMPPS Grendon page)

Grendon is in the national pay zone and is on HMPPS’s Band 3 market supplement list at £1,500 a year (3 October 2026), non-pensionable and, in HMPPS’s words, guaranteed to at least March 2027 and able to be withdrawn.

Our pay data records HMPPS’s annual review as gradually eroding the supplement at Grendon from 1 April 2026. See prison officer pay.

Apply through become a prison officer and compare nearby options in the regional jobs guide.