UK Taxpayers Face £100m Cost After Ministry of Justice Leases Radon-Contaminated Dartmoor Prison

A decision by the Ministry of Justice to enter into a 10-year lease for a prison contaminated with dangerous levels of a toxic gas is expected to cost UK taxpayers more than £100 million, according to parliament’s spending watchdog.

The Public Accounts Committee described the 2022 agreement to lease HMP Dartmoor from the Duchy of Cornwall as a move made “in a blind panic” by senior officials desperate to secure prison capacity. The category C prison, which housed many sex offenders, was shut in 2024 after radon gas levels were found to be as much as ten times higher than recommended safety limits in certain areas.

Radon, a colourless and odourless radioactive gas, is responsible for around 1,100 lung cancer deaths annually in the UK. Although the government has said it was aware of elevated radon readings as early as 2020, the committee found that further testing had not been completed before the lease was signed.

Under the contract, the Ministry of Justice cannot exit the lease until at least December 2033. Despite the prison being unusable, the government is currently paying about £4 million each year in rent, business rates, and security costs. In addition, an estimated £68 million will be spent on structural improvements during the lease period.

Conservative MP Geoffrey Clifton-Brown, chair of the committee, called the handling of the deal “an absolute disgrace,” rejecting claims that the decision was justified by the need for prison spaces. He said the case highlighted a department grasping at any solution under pressure, without proper consideration of long-standing health risks.

The prison’s closure led to the relocation of 682 inmates. Radon monitoring at Dartmoor began in 2010, but the final prisoners and staff were not moved out until July 2024, raising concerns over whether action should have been taken earlier. While the Ministry of Justice has stated that elevated radon levels were first detected in 2020, reports suggest similar findings may date back to 2007.

More than 500 former prisoners and staff are now pursuing legal action, claiming their health was endangered. HMP Dartmoor is owned by the Duchy of Cornwall, which provides private income to Prince William.

An investigation by the Health and Safety Executive, launched in 2023, remains ongoing. The Prison Officers Association welcomed the committee’s findings, condemning the lack of accountability for senior decision-makers and the waste of public funds.

Defending the decision, the Ministry of Justice’s permanent secretary said the lease was signed at a time when the prison system was close to running out of capacity, and that Dartmoor offered over 600 places. A ministry spokesperson added that the current government inherited a prison system on the verge of collapse, posing serious risks to public order.