Diego Garcia Military Base and British Indian Ocean Territory Bill Committee: Amendment 9

Division 315 on 20 October 2025 saw MPs defeat Amendment 9 to the Diego Garcia Military Base and British Indian Ocean Territory Bill by 319 votes to 83. The amendment, tabled by Dr Al Pinkerton, the Liberal Democrat MP for Surrey Heath, would have required the government to negotiate with Mauritius for a legally binding right for Chagossians to return and reside in the Chagos Islands, and to seek Chagossian agreement to a self-determination referendum, before the treaty transferring sovereignty could come into force. The amendment sought to make Chagossian rights a precondition for the treaty taking legal effect. The Bill implements a treaty signed on 22 May 2025 under which Mauritius becomes sovereign over the Chagos Archipelago, including Diego Garcia, with the UK retaining rights to administer and operate its military base there. Supporters of the amendment argued the treaty fails to provide a legally binding right to return or a binding programme of resettlement for Chagossians, the people forcibly displaced from the islands decades ago. Opponents characterised it as a wrecking measure that would prevent the government from meeting its international commitments on a treaty that, they argued, also secures the Diego Garcia base. The vote divided almost entirely along lines of government versus opposition. Labour and Labour and Co-operative MPs voted unanimously against the amendment, providing the bulk of the 319 noes, while the Green Party also voted no. The Liberal Democrats provided the largest share of the 83 ayes, joined by smaller numbers from Reform UK, Plaid Cymru, the Democratic Unionist Party, the SNP, and four Conservatives. The Conservatives had 112 members with no vote recorded. The Bill passed its Third Reading the same day by 320 votes to 171.