GRETA’s warning to the UK: detention, deportation and the trafficking system it refuses to confront
The Council of Europe’s expert group on trafficking in human beings, GRETA, has published its fourth evaluation of the UK for the period covering July 2021 to November 2025.
The Council of Europe’s expert group on trafficking in human beings, GRETA, has published its fourth evaluation of the UK. The report has delivered a damning warning about the UK’s immigration detention system. Buried within its latest evaluation report is a conclusion that detention, deportation threats and hostile immigration policies are increasing the vulnerability of migrants and asylum seekers to trafficking and exploitation.
The report repeatedly returns to one central concern. Immigration enforcement and anti-trafficking protections are moving in opposite directions. For anyone familiar with the history of immigration detention in the UK, the findings feel painfully familiar.
Nearly a decade after the Stephen Shaw reviews exposed systemic harm in detention, and just three years after the Brook House Inquiry documented abuse, degradation and institutional failures inside detention centres, international monitors are still identifying the same structural problems: vulnerable people detained despite clear safeguarding risks, failures to identify trafficking survivors, inadequate healthcare, poor safeguarding procedures, and an immigration system organised around enforcement rather than protection.
The report highlights that the number of people held in immigration detention rose to 20,604 in 2024 — a 12% increase on the previous year. GRETA specifically warns that recent immigration legislation, including the Nationality and Borders Act(NABA) and Illegal Migration Act(IMA), has increased vulnerabilities. It notes that fear of detention and deportation prevents migrants from reporting exploitation or seeking support, a fear traffickers actively exploit to maintain control.
That finding should be read alongside the history of warnings already made about detention.
In 2016 and again in 2018, Stephen Shaw’s independent reviews into the welfare of vulnerable people in detention concluded that detention was causing 'serious harm to people' already experiencing trauma, mental ill-health and vulnerability. Shaw warned that the detention system was too often inappropriate for vulnerable individuals and criticised a culture where detention remained the default administrative response.
One of Shaw’s key recommendations led to the “Adults at Risk” policy, designed to reduce the detention of vulnerable people, including trafficking survivors. Yet GRETA’s findings suggest that this policy continues to fail in practice. The report notes that although guidance requires assessments of whether someone is an “adult at risk” before detention, an inspection by the Independent Chief Inspector of Borders and Immigration found repeated failures by Home Office staff, healthcare providers and contractors to identify vulnerable detainees. Crucially, disclosures relating to modern slavery and trafficking “were not always followed up.”
This echoes a pattern identified repeatedly across detention inspection and inquiries: vulnerability acknowledged on paper but ignored operationally.
The Brook House Inquiry reached similarly devastating conclusions. The inquiry examined abuse at Brook House Immigration Removal Centre between 2017 and 2020 after undercover footage exposed detained people being verbally abused, mocked, threatened and assaulted by detention officers. But the inquiry’s significance went beyond individual misconduct. It exposed systemic failures in safeguarding vulnerable people, failures to identify mental distress, and a culture where detention itself intensified harm.
Former detained people described feeling dehumanised, unsafe and psychologically broken. Staff frequently interpreted distress through the lens of discipline and control rather than vulnerability and trauma. GRETA’s report suggests little has fundamentally changed.
During its 2024 visit, GRETA inspected Heathrow Immigration Removal Centre, which combines Harmondsworth and Colnbrook and is described in the report as “the largest IRC in Europe” and “a prison-like structure managed by a private company.” That description matters. Immigration detention is routinely presented politically as administrative and managerial. But international observers entering these spaces continue to describe environments resembling prisons, operating through confinement, surveillance and coercion.
At Heathrow IRC, GRETA was told staff conduct trafficking and vulnerability interviews within 48 hours of arrival and that people in detention are medically screened. But elsewhere in the report, GRETA documents repeated concerns that trafficking indicators continue to be missed within detention and asylum processing systems. This contradiction lies at the centre of the UK detention system. Safeguarding mechanisms formally exist. Staff receive trafficking training. Screening procedures are in place. Yet vulnerable people continue to be detained, disbelieved and pushed through systems designed primarily around immigration enforcement.
GRETA also raises concerns about conditions at short-term holding sites used for people arriving by small boat crossings, including Manston and Kent Intake Units. Inspectors identified inadequate safeguarding, insufficient privacy, poor interpretation access and delays identifying vulnerable individuals. Again, these concerns mirror previous investigations. The Brook House Inquiry concluded that detention centres routinely struggled to identify and respond appropriately to vulnerability. Shaw repeatedly warned that detention environments themselves worsen trauma and mental ill-health. Independent inspectors have consistently documented failures in healthcare, safeguarding and Rule 35 processes — the mechanism intended to identify people whose health is being harmed by detention.
GRETA now adds another layer: detention is not only harming vulnerable people, but actively increasing trafficking risk. The report draws a direct connection between hostile immigration policy and exploitation. Restrictions on asylum support, barriers to legal aid, the threat of detention and exclusion from mainstream support systems are all identified as factors increasing vulnerability to trafficking.
Importantly, GRETA also criticises the “public order disqualification” provisions introduced under the NABA, which allow trafficking survivors to be denied protection. In practice, this reinforces a system where vulnerability is increasingly interpreted through suspicion and criminalisation. This was one of the underlying themes of Brook House too: people in detention were often viewed first through the lens of immigration control and risk management, rather than as people with histories of trauma, torture, trafficking or mental distress.
The government’s response to GRETA largely points to updated guidance, staff training and safeguarding procedures. But this is also familiar territory.
- After Brook House, the government promised culture change.
- After Shaw, it promised a humane system, reduction to detention and focus on alternatives.
- After repeated inspections, it promised better safeguarding.
Yet GRETA’s report demonstrates that the core architecture remains intact: detention continues to function as a coercive arm of border enforcement, and vulnerable people continue to fall through the cracks.
The most striking aspect of GRETA’s findings is not simply that problems persist. It is that international monitors are now explicitly linking detention policy itself to trafficking vulnerability. That should force a more uncomfortable conversation.
Because if detention, deportation threats and hostile immigration controls are making people more vulnerable to trafficking, then these are no longer merely failures of implementation.
They are structural harms built into the system itself.
The government response lists mechanisms. GRETA is asking whether those mechanisms actually protect people.
That is the question this report leaves us with: not whether the UK has policies, guidance, training and contracts, but whether a person who has been trafficked can safely disclose, be believed, access support, avoid detention, challenge removal, recover, and rebuild.