Why is Britain handing over the Chagos Islands to Mauritius?

Independent

23-05-2025

After some last-minute legal delays, the Chagos Islands treaty between the UK and Mauritius has been signed, and will almost certainly be implemented in the coming weeks.
The great controversies about the UK-US military base in this remote stretch of the Indian Ocean have passed most of Britain's population by, but for some the issue remains a matter of passionate concern, and the charge of 'treason' has been lobbed at the prime minister. The arguments won't go away...
What happens next?
In the UK, there will have to be a parliamentary debate and approval within 21 (sitting) days of the signature, and given that the Commons is in recess again for a week, things won't be finalised for a while.
In the past, international agreements would be signed under the royal prerogative, thus averting the need for formal legislative approval. However, this is now required under the Constitutional Reform and Governance Act 2010, and the provisions of the treaty ought to be enshrined in domestic law (including the Mauritius Independence Act 1968).
Given Labour's overwhelming majority, the treaty is bound to be ratified, but Priti Patel for the Conservatives, along with Reform UK, will put up a fight.
What difference will it make?
It will settle for at least a century the status of the Chagos Islands, including the base on Diego Garcia, and thus make the area safe from any further action under international law.
Why are we giving the Chagos Islands away anyway?
Arguably, the UK is not giving the Chagos Islands 'away', but 'back' to their rightful owner, Mauritius. They were carved out of the old Mauritius crown colony in 1965 as a condition for granting the rest of the territories independence, which came three years later.
A new colony, now a British Overseas Territory, of the British Indian Ocean Territory was created to administer the area. It will soon disappear, and the islands will be Mauritian sovereign territory, the base area leased back for 99 years with an option to renew.
Why can't we just carry on as we are?
We could, but it's getting more hazardous. First, because the ownership of the islands is under dispute, and multiple UN and International Court rulings have said they belong to Mauritius. More adverse decisions are on the way, too.
Although these have been safely ignored by the British and Americans for decades, it's hardly ideal. One risk is that Mauritius could lawfully grant, say, China or India permission to establish a military base on another of the islands, and that would spark a serious crisis to say the least.
Another practical threat is highlighted by the defence secretary, John Healey: 'The most proximate, the most potentially serious, is the tribunal of the international Convention [on the Law] of the Sea.'
If the government lost a case there, the government says, other countries and UN agencies would be obliged – by international law – to take decisions that would hamper the operations of the base. In addition, Diego Garcia's satellite communications would be in jeopardy, because the UK relies on a UN agency in Geneva to maintain access to a particular electromagnetic spectrum.
Company contractors nervous about international law might refuse to come to the base, while international regulations on air travel might also make passage to the islands more difficult.
What will it cost?
Some £101m a year, plus additional development aid for Mauritius. Some of this will be index linked, but it's spurious to try to translate it into prospective cash terms at 2124 price levels. The UK will pay the lease, with no US contribution. Keir Starmer argues, in effect, that UK national security also benefits from the base, and the money is worth spending to help preserve the ' special relationship ' with America.
What about the Chagossians?
There are none left on the islands to consult or to take part in a referendum. In a shameful episode during decolonisation, they were deported, with most settling in Mauritius, the Seychelles and the UK. Many oppose the deal, but their legal actions have failed.
Is the base useful?
Certainly to the US, as a centre for space communications and communications surveillance, and for bombing raids in the Middle East. It is also useful as a base for aircraft carriers, among other things.
Does it matter politically?
The opposition parties are weaponising the deal as proof that Labour is weak and basically unpatriotic, hence the Tory slogan 'when Labour negotiates'. Irrelevant to domestic political issues, for some it will become totemic, as was the case when Gordon Brown as chancellor sold off some of the UK's gold reserves for equally rational reasons.
The Chagos Islands deal, then, provides a handy source of dishonest jibes for the Tories and Reform, but won't seal the fate of the Starmer administration at the next election.