The UK-France Migrant Deal Has Been Locking Up Children as Adults
Nearly 100 children were wrongly identified and locked up as adults under a UK-France migration deal, according to figures reported by the Guardian on 13 August 2026. The data comes from a letter by Jane Leech, who leads independent monitoring boards — independent groups that watch conditions in UK detention centres. Out of 304 cases where a person's age was in question, 94 — about 31% — turned out to be children Guardian.
In the UK, it is illegal to hold children who arrive alone (without a parent or guardian) in adult detention centres. Government rules also say these children should only be held for up to 24 hours. Despite these rules, the monitoring boards found that these protections were not being followed under the scheme, which the Home Office calls Operation Hillmore Guardian.
The deal, launched in August 2025, works on a 'one in, one out' basis: the UK can send certain people who arrive by small boat back to France, and in return takes in the same number of people from France who are judged to have a genuine claim to protection. From 4 August 2025 to 30 June 2026, 1,087 people were sent back to France under the deal. During that same period, 27,920 people arrived in the UK on small boats Guardian.
Leech's letter to Home Office minister Anna Turley lists several other concerns. She said some people were held for more than six months even though the rules say detention beyond 28 days should only happen 'in exceptional cases.' One man was held for 27 weeks under a scheme meant to work quickly. Some people were being prepared for removal to France despite having tuberculosis or needing hospital treatment. The monitoring board at Heathrow saw a person with tuberculosis sent to a Gatwick detention centre, and another person was turned away from Brook House detention centre because of critical health and sent straight to hospital. Poor health checks at a holding site called Manston were specifically flagged Guardian.
Leech also reported that some people were sent for removal after being split from family members they had travelled with, which she said had a 'particularly damaging impact.' She called the deal 'placing highly vulnerable, newly arrived individuals, including children and survivors of abuse, in detention.' Many of those held were psychologically distressed, and monitors saw records and heard testimonies showing that many are survivors of torture and abuse Guardian.
In two cases seen by the Heathrow board, it took 40 days or more from when someone arrived at a detention centre to when their age was checked. That delay meant people who turned out to be children spent long stretches locked up with adults Guardian.
The 94 confirmed cases of children being detained are the latest and largest number in a growing pattern. A Guardian report on 5 April 2026 found 76 age-disputed children held under the scheme. By mid-May 2026, a charity called JRS UK reported at least 141 age-disputed young people detained since the scheme began. By 24 June 2026, a group called the Humans for Rights Network (HFRN) had identified 174 age-disputed young people detained, 25 of whom had been sent to France Oxford Border Criminologies Blog. Freedom of information data published on 29 May 2026 also showed that lone children were held at UK-run detention centres in France Guardian.
The problem with age assessment has structural roots. Home Office data shows that local councils — which provide social services for children — judge young arrivals to be children more than twice as often as border force officials do Guardian. Under government policy, a person's age can be questioned either by the Home Office, usually when they first claim protection, or by local council children's services gov.uk. A body called the National Age Assessment Board, set up under the Nationality and Borders Act 2022, was meant to make this process more consistent. Before 2019, immigration officials had broad freedom in how they handled age disputes gov.uk.
More than 100 organisations warned in June 2026 that a UK plan to use computer software (AI) to assess the age of young asylum seekers could result in more children ending up in adult detention Guardian. In July 2026, a court ruled that Britain acted unlawfully by removing asylum seekers' right to challenge decisions that rejected their claim to be a victim of trafficking (where people are exploited or traded illegally), in a case linked to the UK-France deal Reuters. In April 2026, the UK and France agreed a new three-year deal on managing unauthorised migration, including small-boat crossings Commons Library.
Imran Hussain, a senior figure at the Refugee Council, called the monitoring board figures 'disturbing' and said they were the latest example of children being wrongly treated as adults by the Home Office Guardian.
The broader context here is one of ongoing tension between detention rules, age-assessment practices, and international cooperation. The monitoring board findings, coming alongside a court ruling that the government acted unlawfully on trafficking-status challenges and growing evidence from charities of child detentions, raise serious questions about whether the scheme's design — which assumes quick age checks, health screening, and removal — fits with the legal protections meant for children and the government's own rules. The data showing a 31% rate of wrongful adult classification among age-disputed cases suggests that the first check done at arrival is systematically less protective than a later review by local councils. Whether the Home Office's planned use of AI for age assessment will narrow or widen that gap is a question the 100-organisation coalition has already raised. The scheme's extension under the April 2026 three-year agreement means these tensions are now built into a framework designed to last through 2029.
