The government’s “one in, one out” returns policy has ensnared dozens of children in adult detention centres, raising serious questions about its legality.

When the British government unveiled its “one in, one out” scheme last year—an arrangement whereby each unauthorised Channel crossing triggers the deportation of one person to France, offset by a legal admission of another—ministers presented it as a firm but orderly solution to an intractable problem. The reality, as is so often the case with asylum policy, has proved messier and more troubling.

Research by the Humans for Rights Network, a civil-society organisation, has identified 76 individuals whose ages were disputed by the Home Office and who were held in adult immigration detention centres in preparation for forced removal to France. The problem with this practice is a straightforward one: it is unlawful to detain unaccompanied child asylum seekers in adult facilities. Of the 76 cases identified since the scheme launched last September 26 have since been released into the care of children’s social services, where many have subsequently been assessed to be minors. Thirteen were removed to France before that determination could be made.

The nationalities involved reflect the geography of contemporary conflict. Eritreans, Sudanese, and Afghans make up the bulk of those caught in this administrative limbo, populations shaped by wars, famines, and authoritarian regimes whose victims need little additional adversity. Many are, according to Maddie Harris of the Humans for Rights Network, survivors of torture or trafficking, experiencing acute deterioration in their mental health because of extended detention.

“No child should be detained.” Maddie Harris, Humans for Rights Network

The legal position is becoming harder for the government to defend. Freedom of information requests to local authority children’s services have revealed a persistent pattern: individuals classified as adults by the Home Office on arrival have repeatedly been reassessed as children once social workers—rather than border officials—conduct their evaluations. In one particularly striking case, a person removed to France under the scheme as an adult was later found by social workers to be a child.

The courts have begun to take notice. On March 25th, the High Court halted the removal of two age-disputed individuals, accepting that the Home Office’s contention, that a person’s age need not be formally determined before they are deported, warranted proper judicial scrutiny. Elizabeth Cole, a solicitor at Duncan Lewis who represented one of the claimants, described the government’s position as “highly concerning”.

The independent chief inspector of borders and immigration has since called for evidence in preparation for a formal investigation into the returns programme. The government has built its small-boats policy around the deterrent logic of firm and swift removals. Whether that logic can survive sustained legal challenge or the awkward spectacle of children being packed onto deportation flights remains to be seen.

Source: The Guardian, 5 April 2026; reporting by Diane Taylor