HMP Dartmoor

Status: temporarily closed

In shortHMP Dartmoor is not operating as a prison: it has been temporarily closed since August 2024 because of radon gas, so there is nothing to apply to.

• Closed sinceAugust 2024Following the detection of radon gas
• Operational capacityZeroHMPPS monthly figures, August 2026
• Spent on radon mitigation£1.2 millionAbout; per the written answer of 29 January 2026

In a written answer on 29 January 2026, the Minister of State for Justice, Lord Timpson, said the prison ‘has been temporarily closed since August 2024 following the detection of radon gas’ and that specialists had been engaged to assess reopening options.

The GOV.UK page for the prison carries a closure message added on 5 September 2024.

In a letter to the Justice Committee dated 15 May 2026, Lord Timpson said the department continues to assess safety and feasibility to determine whether the site can be reopened as a prison.

The Ministry has said a reopening decision would rest on the viability of the site, the effectiveness of works to reduce radon, and value for money.

History and role before closure

In shortDartmoor was established in 1809 and, before closing, was a category C training prison for adult men with 684 prisoners at its 2023 inspection.

HM Inspectorate of Prisons (HMIP) records that the Chief Inspector called it ‘one of the oldest jails in the country’. At its last inspection, in 2023, HMIP described it as a category C training prison holding adult men, with 684 prisoners at the time against an operational capacity of 689.

The accommodation was arranged in wings known as Tors, such as Arch Tor, Burra Tor and Down Tor, each integrated for mainstream prisoners and men convicted of sexual offences, plus a small segregation unit.

The last inspection: June to July 2023

In shortHMIP’s 2023 inspection found relationships a real strength but purposeful activity poor, with 13 key concerns, five of them priorities.

• SafetyReasonably good
• RespectNot sufficiently good
• Purposeful activityPoor
• Rehabilitation and release planningReasonably good

HMIP’s unannounced inspection ran from 19 June to 6 July 2023, and the report was published on 9 October 2023.

The Chief Inspector wrote that relationships between staff and prisoners were a real strength, although some officers’ behaviour was affecting a generally positive culture, and that peer work, including the Peaceful Solutions scheme, was helping some troubled prisoners.

• Weak oversight of the regime, which inspectors found curtailed more than 80% of the time.
• An inconsistent daily routine.
• Health care staffing shortfalls after a change of provider.
• Too few suitable education and work places, and low achievement in education, skills and work.
• Doubling up in 49 cells, large amounts of drugs entering the prison and a health care environment that was not fit for purpose.
• HMIP said the prison had done well to keep the buildings clean despite their condition.

Radon and the road to closure

In shortElevated radon was found in 2020, the population fell sharply through 2023 and 2024, and the Health and Safety Executive censured HMPPS in May 2026.

The Independent Monitoring Board’s report for October 2023 to September 2024, published in December 2024, explains the monitoring history. The IMB said the reporting year was dominated by the response and ended in the decision to close temporarily in August 2024.

The Health and Safety Executive (HSE) said on 13 May 2026 that it was authorising a Crown Censure of HMPPS, finding that the prison service failed to adequately manage radon exposure at Dartmoor and that prisoners and staff were exposed above legal limits.

• HSE said it was first notified of suspected overexposure in February 2023 and took enforcement action in February and December 2023.
• A Crown Censure is the maximum sanction against a Crown body and carries no financial penalty.
• HMPPS monitors radon across the estate under the Ionising Radiations Regulations 2017.

What closure meant for staff and neighbouring prisons

In shortClosure made staffing difficult at Dartmoor and raised staffing at Channings Wood, but there is no live recruitment at Dartmoor.

The IMB reports that during the decant, staffing was difficult and that there was a question over the viability of previous staffing levels as numbers fell, while some prison industries and peer-support schemes lost members.

The Channings Wood IMB report says that prison’s staffing rose after the closure of Dartmoor, and that its population now has an older profile because of transfers from Dartmoor. For current regional context, see our guide to prison officer jobs by region.