Hundreds of cells are empty at Britain’s new-build prison in Yorkshire more than a year after opening.
Government officials and Mitie, who run the prison HMP Millsike, have defended the empty spaces, saying that there is a phased build-up plan in place. This comes as justice secretary Alex Norris is facing a scramble to find prison space this summer after prime minister Andy Burnham partially reversed plans to release some prisoners early.
According to Ministry of Justice (MoJ) statistics from July, the maximum capacity at HMP Millsike will be 1,468 when it is fully up and running. The category C prison for low to medium-security inmates now has an operating capacity of 1,158 cells with a population of 1,124 – meaning more than 300 cells are laying empty.
MoJ officials say it is important for safety reasons for new prisons to be opened up gradually, with staff needing to adapt to a new site and establish the culture and regime.
Independent inspectors raised concerns at the end of last year about safety and security at HMP Millsike, which opened in March 2025. They said that inexperienced staff inevitably require considerable time to gain the confidence, skills and experience needed to operate the site safely.
The Independent Monitoring Board said the “cumulative impact of this inexperience is being felt across almost every aspect of prison life”, with some prisoners spending up to 23 hours per day in their cell.
The prime minister has ordered justice secretary Mr Norris to find a way to prevent the early release of two teenagers found guilty of the manslaughter of PC Andrew Harper.
A senior prison source told The Telegraph that HMP Millsike has been “struggling to staff the prison”, adding: “They have reached the point where they have got all the staff they can recruit to safely operate at a reduced number of spaces but they are struggling to get above that.”
The source added: “They are experiencing what most prisons are facing. We are recruiting people, training them, then they are leaving.”
A Mitie spokesperson said: “HMP Millsike continues to operate in line with the ramp up plans agreed with the Ministry of Justice, with staffing and recruitment aligned to the prison’s phased population build-up. We remain focused on maintaining a safe, secure and supportive environment for prisoners and colleagues.”
A MoJ spokesperson said: “This government inherited a prison capacity crisis after prison places increased by just 500 places in 14 years. We are pulling every lever possible to fix that crisis and are building 14,000 new places with 3,200 already delivered.
“We are working at pace to bring every available prison place online – and have always been clear new prisons require a ramp up period to ensure they remain safe, secure and protect the public.
“We are also exploring how we can go further to increase capacity, including faster deportation of foreign criminals, better use of the women’s estate and reviewing the unjust IPP sentences.”
