For the cession of the Chagos Islands to go ahead, the Government must persuade the US Administration to support its agreement with Mauritius and to amend the 1966 US-UK treaty concerning the availability for defence purposes of the British Indian Ocean Territory. It must also persuade Parliament to enact the legislation – the Diego Garcia Military Base and British Indian Ocean Territory Bill – that is necessary to ratify the agreement with Mauritius.

This research note considers the case for ceding the Chagos Islands to Mauritius and shows it to be wanting.  The risks of walking away from the new Treaty and maintaining UK sovereignty have been greatly exaggerated.  The risks of ratifying the new Treaty and ceding the Chagos Islands to Mauritius have been greatly underappreciated.  In addition, surrendering the Chagos Islands to Mauritius compounds rather than addresses the historic injustices done to the Chagossians. It also heightens the risk of an environmental catastrophe in the Indian Ocean, with a priceless marine environment open to being exploited and degraded.