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Nearly 100 children were wrongly identified as adults and detained under the UK's migrant returns arrangement with France between August 2025 and May 2026, according to figures disclosed by Home Office officials. Independent monitors have warned that safeguarding procedures may be failing, while raising concerns over lengthy detention periods, healthcare provision and the treatment of vulnerable asylum seekers.
The UK Government is facing renewed scrutiny over its "one in, one out" migrant returns agreement with France after official figures revealed that 94 children were wrongly detained as adults before later being recognised as minors.
Daily Dazzling Dawn understands the figures emerged in correspondence sent by Jane Leech, interim chair of the Independent Monitoring Boards (IMBs), to Home Office minister Anna Turley. The letter detailed concerns about the operation of the scheme, formally known within the department as Operation Hillmore.
According to the data, 304 age-disputed cases were recorded between 15 August 2025 and 1 May 2026. Of those, 94 individuals — representing 31 per cent of cases — were ultimately assessed to be children.
Leech wrote: "Your officials have informed the IMB that 304 age disputes have taken place between 15 August 2025 and 1 May 2026, of which 94 (31%) were assessed to be children."
She added: "The IMB is therefore concerned that child safeguarding mechanisms are ineffective, and believes more should be done to ensure that those whose age is under dispute are not detained in the first place."
Current government policy generally limits the detention of unaccompanied children to a maximum of 24 hours, while minors are intended to be excluded from the returns scheme altogether.
The monitoring body also raised concerns over delays in determining the ages of those whose status was disputed.
Leech said some assessments took weeks to complete after individuals had already entered immigration detention facilities.
"In two cases observed by the Heathrow Board, it took 40 days or more from arrival at the IRC to age assessment," she wrote.
The findings are likely to increase pressure on ministers to review age-assessment procedures, particularly where uncertainty exists over whether newly arrived migrants are adults or children.
The letter also highlighted concerns surrounding healthcare screening and the treatment of vulnerable detainees.
Daily Dazzling Dawn learned that monitors recorded cases involving individuals who were allegedly being prepared for removal despite serious medical conditions.
"There was evidence of poor health screening at Manston among the Hillmore detainees," Leech wrote.
She added: "Gatwick IRC recently received one individual from Manston with tuberculosis, while a second was refused admission to Brook House because of the critical state of their health, and referred directly to hospital."
Leech further warned that many detainees appeared psychologically distressed and vulnerable.
"Many of those who have recently arrived present as psychologically distressed, and Boards have observed records and heard testimonies showing that many are survivors of torture and abuse," she wrote.
Questions have also been raised about the length of time some individuals have spent in detention despite the scheme being designed to operate quickly.
The monitoring body reported cases in which migrants remained detained for months while awaiting removal. One individual was reportedly held for 27 weeks.
Leech said some detainees had been waiting for deportation for more than six months, despite the expectation that detention beyond 28 days should occur only in exceptional circumstances.
The IMB also expressed concern about people being separated from family members during the removal process, warning that such decisions could have a particularly damaging impact on vulnerable individuals.
The UK-France arrangement, launched in August 2025, allows Britain to return certain people arriving by small boat to France while accepting an equivalent number of individuals from France who are deemed to have a legitimate basis for claiming asylum in the UK.
Government statistics covering the period from 4 August 2025 to 30 June 2026 show that 1,087 people were returned to France under the agreement. During the same timeframe, 27,920 migrants arrived in the UK via small boats.
Imran Hussain, Executive Director of External Affairs at the Refugee Council, described the figures as deeply concerning.
"Too often refugee children are being treated as adults and put into unsafe situations, at risk of abuse and neglect, and exposed to significant safeguarding risks," he said.
"We call on the government to prioritise professional assessments led by trained social workers, which has been found to be the most accurate way to determine age and therefore avoid these risks."
The latest disclosures are expected to fuel further debate over the operation of the returns scheme, with ministers likely to face renewed calls to strengthen safeguarding procedures and improve protections for children and other vulnerable asylum seekers entering the UK's immigration system.
