Opposition Day: British Indian Ocean Territory

What happened: The House of Commons voted on 26 February 2025 on a Conservative Opposition Day motion criticising the Labour government's decision to transfer sovereignty over the British Indian Ocean Territory (BIOT) to Mauritius. The motion was defeated by 298 votes to 147. Opposition Day motions are parliamentary debates initiated by opposition parties, allowing them to choose the topic and put a formal vote to the House, though such votes are not legally binding on the government.

Why it matters: The vote reflects the political temperature around one of the most significant British foreign policy decisions in recent years. The agreement would transfer sovereignty of the Chagos Islands, part of BIOT, to Mauritius, while the UK and United States would retain rights to operate the strategically vital Diego Garcia military base for an initial period. Critics argue this weakens British and Western security interests in the Indian Ocean, while the government contends it secures the long-term future of the base and resolves a long-running legal and diplomatic dispute rooted in the 1960s displacement of the Chagossian people.

The politics: Labour MPs voted unanimously against the motion, with Conservative, Liberal Democrat, and Reform UK MPs all voting in favour of opposing the deal. The Liberal Democrats' support for the motion is notable, as the party has generally taken a more internationalist and pro-multilateral stance, but backed the opposition position here, suggesting broad unease about the terms of the agreement across the political spectrum. The vote falls within a sustained period of parliamentary pressure on the government over defence and security matters, with several related divisions on the Armed Forces Commissioner Bill in January 2025 also resulting in government victories.