An independent inspection of the UK-France agreement on small-boat crossings has found that the pilot scheme known as Operation Hillmore proved a linked returns arrangement could work, but that ministers never set clear criteria for judging whether it succeeded.

The report by the Independent Chief Inspector of Borders and Immigration, John Tuckett, was published on Tuesday 10 November 2026. It covers the pilot from March to June 2026, and the Home Office has accepted all three of its recommendations.

What was Operation Hillmore?

Operation Hillmore was a ten-month pilot under which people who arrived in the UK by small boat could be returned to France, while an equal number of eligible migrants in France could enter the UK through a controlled legal route. It became known informally as the “one in, one out” arrangement.

The pilot was set up at speed and was due to end on 11 June 2026, but was extended until 1 October 2026. The Home Office confirmed in September that the scheme would no longer process new cases.

Home Office figures show that between 4 August 2025 and 30 June 2026, 1,087 people were returned from the UK to France under the pilot, while 1,117 people were transferred from France to the UK. Over the same period, 27,920 migrants arrived in the UK by small boat, meaning about 4 per cent of arrivals were returned under the scheme.

What the inspectors found

The inspection found that the pilot demonstrated that a jointly linked agreement for returns and legal transfers “could be established and made to work using existing practices and ways of working that were legally robust”.

Inspectors also praised the pilot’s leadership, governance, collaborative working and operational delivery. But the report found a significant weakness: clear criteria for assessing the overall success of the pilot were not established at the outset.

The pilot’s stated aims focused on high-level strategic objectives, such as deterring migrants from using small boats, where many other factors were also in play. The inspectors said this made it difficult to evaluate Operation Hillmore’s specific contribution to any reduction in small-boat arrivals.

Cost and recommendations

Home Secretary Shabana Mahmood told MPs in September that returning a migrant under the arrangement cost the UK taxpayer an average of about £56,000.

The inspection report makes three recommendations to strengthen the design, delivery and evaluation of future Home Office pilots. The Home Office said work was already under way on aspects of the improvements, and that it would use the findings to inform future decisions on Operation Hillmore and any later migration pilots.

The report was sent to the Home Secretary on 16 July 2026. The Home Office said it welcomed the recognition of the “significant achievement” of developing and delivering a complex international pilot at pace.

What happens next

The Government has said there are no current plans to resume the scheme once operational activity has concluded, although cases opened before the pilot ended have continued to be processed. The inspection’s lessons are expected to feed into any future UK-France or wider migration arrangements ahead of the UK-EU summit scheduled for 20 November.