Beyond building prisons: addressing the human impact of overcrowding in places of detention

Despite some positive policy changes and staffing improvements over the past year, the 2024 national annual report from the Independent Monitoring Board (IMB), published today (19 June 2025), reveals that places of detention, including prisons, young offender institutions (YOIs), and immigration detention facilities, continue to grapple with deep-rooted issues. Concerningly, IMBs report a level of acceptance among some staff and detained people, with poor conditions becoming normalised after years of inaction and minimal change; prisoners often feel there is no point in complaining and staff have become desensitised to seeing people in acute distress.

Severe overcrowding, largely due to longer sentences and rising rates of imprisonment, coupled with inadequate focus on rehabilitation, has created a ripple effect that is now impacting the immigration detention estate under Operation Safeguard. As prisons reach their capacity limits, higher numbers of foreign national offenders at the end of sentence are being redirected to immigration removal centres (IRCs), which are not sufficiently equipped to handle such an influx. This has further strained resources and complicated the management of both prisons and immigration detention, making it increasingly challenging to support the, often complex, needs and well-being of the men, women and children held there.

IMBs reported the following:

Excessively high levels of violence and substance misuse.

Violence was driven by overcrowding, inadequate mental health support, and surges in drug use, all of which created volatile environments.

• At HMP Eastwood Park, restrictions to the daily routine often disrupted the stability of the prison as women engaged in protesting behaviour, often lashing out at staff or other prisoners.
• At HMP Pentonville, a great deal of staff resource was spent on separating prisoners and arranging appropriate transfers to minimise conflict.
• Werrington IMB reported a 39% increase in the number of children self-separating because they were frightened of other children.
• At Harmondsworth and Colnbrook IRCs, the IMB observed an increase in violence and altercations, with staff unable to maintain a safe environment.
• At Brook House IRC drug dealers were thought to have used vulnerable men as guinea pigs to test drugs, with one man requiring medical care on several occasions as a result.

High numbers of people at risk of suicide or self-harm.

IMBs reported on rising levels of self-harm, with improvements needed to safeguard those at risk.

• At Feltham YOI, self-harm incidents increased significantly from 3.5 per 100 children in February 2024 to 23.8 in May. This was partly attributed to the growing population and anxiety over Cookham Wood arrivals, as well as a decline in effective staffing levels.
• At Werrington YOI glass observation panels in cell doors were frequently smashed, and there were several incidents of children subsequently swallowing broken glass.
• Essential health screenings to identify vulnerabilities on arrival in immigration detention were inconsistently conducted, leading to those whose health is likely to be injuriously affected by detention being wrongfully detained and critical care opportunities being missed.

Concerning use of force on those detained.

Prison IMBs reported that use of force was used disproportionately and poorly scrutinised, while IMBs in immigration detention observed an increase in the use of force, with the principles of usage not always followed.

• Young adults and neurodivergent prisoners were overrepresented in use of force incidents, with 74% of those affected at Brixton registered as disabled; racial disproportionalities were also concerning, with black prisoners at Elmley significantly more likely to experience force than their white counterparts.
• Boards reported that inexperienced staff struggled to de-escalate incidents and the IMBs at Hewell and Chelmsford were concerned that staff inexperience was behind an increase in the use of force. This was supported by prison staff at Altcourse who told Board members that experienced staff were unlikely to need PAVA or batons.
• Boards across the immigration detention estate observed a blanket approach to handcuffing, which should only be used as a last resort; Gatwick IMB found that close to 100% of people taken to hospital appointments were handcuffed.
• At Yarl’s Wood, women were threatened with the use of handcuffs by an officer if they did not agree to a transfer to Derwentside, an IRC hundreds of miles away that would make visits from family or legal advisers highly unlikely.

Elisabeth Davies, IMB National Chair said:

“As National Chair, I acknowledge that past underinvestment has shaped the environments that IMBs now monitor. It’s time to rewrite the narrative. IMBs deliver crucial insight, exposing systemic issues across places of detention and revealing patterns between prisons, young offender institutions and places of immigration detention. Yet, these issues remain unaddressed, and I find myself echoing the same concerns, alongside new ones, a year later.

We must act to effectively rehabilitate those who will eventually leave prison and YOIs to curb reoffending, and manage vulnerabilities in immigration detention to build pathways to stability.

Investing in these environments and the people detained there is also an investment in staff – not only creating safer spaces for detained people, but also fostering a more secure and supportive working environment.”