Political sources say Keir Starmer may push for ratification as early as 10 February and impose a three line whip on Labour peers forcing through the Chagos surrender.
Fresh political turmoil surrounding Peter Mandelson is intensifying pressure on the Labour government over its controversial agreement to hand sovereignty of the Chagos Archipelago to Mauritius, with critics now demanding the treaty be paused until the United States completes its own security assessment.
The renewed focus follows the release of documents in the United States linked to the Jeffrey Epstein case, which prompted police reviews in Britain and led Mandelson to resign from the Labour Party.
The veteran New Labour figure, who previously served as Britain’s ambassador in Washington and held senior Cabinet posts, now faces the most serious crisis of his public life.
Opponents of the Chagos agreement argue that the controversy undermines confidence in the government’s foreign policy judgment at a moment when Parliament is still required to ratify the treaty.
Under the deal, agreed in principle in 2024 and signed in 2025 but still not ratified, the United Kingdom would transfer sovereignty of the archipelago to Mauritius while retaining long term rights to operate the strategically vital military base on Diego Garcia. Labour Ministers say the arrangement secures Western defence interests and resolves a decades long legal dispute. However, critics on both sides of the Atlantic dispute that assessment, warning of Chinese espionage, environmental risks to one of the world’s largest marine protected areas, geopolitical consequences in the Indian Ocean and discrimination towards the Chagossians themselves.
The United States has emerged as a central player in the security argument. President Donald Trump has publicly criticised the agreement calling it a deal of “great stupidity”, while several American lawmakers have urged closer scrutiny of its implications for the joint base. In Westminster, Conservative MPs and peers have echoed those concerns, arguing that ratification should not proceed until Washington has completed a full review.
The controversy now collides with the political fallout from Mandelson’s case. After previously endorsing him, Keir Starmer has now said Mandelson should no longer sit in the House of Lords and has backed reforms to disciplinary procedures in the upper chamber. The episode has fuelled accusations from opponents that Starmer exercised poor judgment in elevating Mandelson to senior diplomatic roles that included involvement in negotiations with the United States, particularly after security officials were reported to have raised concerns about the appointment which were ultimately overridden by the Prime Minister.
Campaigners against the Chagos transfer have begun framing the treaty as inseparable from Mandelson’s influence inside government, pointing to his long standing role in shaping foreign policy debates and his close ties to senior figures from the New Labour era, including Jonathan Powell. They claim that he acted as a chief advocate for the deal in Washington and as a key voice in shaping Britain’s broader strategic posture in the region, including its approach to China.
Government officials reject that characterisation, saying negotiations were led by the Foreign Office and defence chiefs rather than by any single political figure. However, it is well documented that Mandelson made visits to key US state departments last year and attended meetings at which undisclosed amendments were discussed in relation to the Diego Garcia treaty notes. Critics argue that the combination of his personal crisis and the unresolved controversy over the islands has significantly raised the political stakes.
Environmental groups also remain highly alarmed about the future of the Chagos reserve, which covers more than 640000 square kilometres and is regarded by scientists as one of the most pristine tropical marine ecosystems on Earth. They fear that changes in governance could eventually open the door to commercial fishing or development across islands that have largely been closed to human settlement for decades.
The Chagossians themselves also had an urgent judicial review permission hearing in October that was championed by the Great British PAC. The PAC’s CEO, Claire Bullivant said, “The Chagossians still have not had judgement. why? Parliament is now being asked to conclude matters of sovereignty before the court has even ruled. That cannot be right. Justice delayed is justice denied. Where is their judgement?”
With Parliament yet to complete ratification, legal rulings unresolved and American debate still ongoing, pressure is mounting on ministers to slow the process. However, political sources say Keir Starmer may attempt to push the agreement through as early as 10 February and could impose a three line whip, requiring Labour peers to support the measure in a decisive vote.
Critics say the government should wait until the United States has finished assessing the strategic risks and until questions surrounding Mandelson’s conduct are fully examined.
For now, the Chagos agreement has become entangled with a wider crisis of confidence in Labour’s foreign policy leadership, one that threatens to dominate Westminster in the days ahead as investigations continue and the fate of one of the world’s most remote island chains hangs in the balance.
Main Image: Cropped image taken in February 2025 in Washington D.C., United States. Prime Minister Keir Starmer walks with Peter Mandelson, UK Ambassador to the United States of America, at the British Embassy to the United States of America. Picture by Simon Dawson / No 10 Downing Street https://creativecommons.org/licenses/by-nc-nd/2.0/
