Chagos, Diego Garcia And The £101 Million Question

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The debate around the Chagos Islands has collapsed into caricature.

Britain is either shamefully surrendering territory or nobly correcting colonial history. The government is either defending the West’s most important Indian Ocean base or handing it away under legal pressure from its own social circle.

None of those summaries explains the numbers. None properly examines the strategy.

If we are going to debate Chagos seriously, we need to separate law from optics, sovereignty from capability, and rhetoric from arithmetic.

This did not begin in 2025

The Chagos Archipelago has been under British control since 1814, following the Treaty of Paris under which France ceded Mauritius and its dependencies to Great Britain.¹

In 1965, before Mauritian independence, the UK detached the islands and created the British Indian Ocean Territory.² Between 1967 and 1973, the Chagossian population was removed to enable construction of the joint UK–US base on Diego Garcia.³

Since then, three distinct issues have run in parallel:

Mauritius’ claim that detachment before independence was unlawful
The rights and return of the Chagossian people
The strategic importance of Diego Garcia

They are related, but they are not the same argument.

In 2019, the International Court of Justice issued an advisory opinion stating that decolonisation had not been lawfully completed and that the UK should end its administration “as rapidly as possible”.⁴

The UN General Assembly subsequently adopted Resolution 73/295 welcoming that opinion and calling on the UK to withdraw its colonial administration.⁵

Advisory opinions are not binding judgments in the same manner as contentious ICJ cases, but diplomatically they matter.

The legal and diplomatic pressure on the UK has been building for years. The 2025 agreement with Mauritius must be understood in that context.

Diego Garcia is not symbolic

Diego Garcia is Under the 1966 Exchange of Notes between the United Kingdom and the United States:

- - - - The UK retained sovereignty
        
        The United States was granted use of the base
        
        There was no rental payment
        
        The US funded operational and infrastructure costs

This position has been confirmed in Parliamentary written answers, which state that no direct payment is made by the United States to the United Kingdom for use of Diego Garcia under the governing arrangements.⁶

Under the new agreement, sovereignty transfers to Mauritius and the UK will reportedly make an annual payment of approximately £101 million in order to retain operational control for 99 years.⁷

That figure is politically potent but it is only part of the story.

The £101 Million Optic

The United States does not pay rent to the UK for Diego Garcia.

It never has.⁸

Washington funds the operational and infrastructure costs of the facility. But there is no cheque to the UK Treasury.

So the British taxpayer now sees:

A visible nine-figure annual payment to Mauritius
No visible American offset
Simultaneous US pressure on NATO members to increase defence spending

That combination creates a perception problem.

NATO, Tariffs and the Burden-Sharing Paradox

Donald Trump has repeatedly criticised members of NATO for failing to meet the 2 percent of GDP defence spending guideline.⁹

European governments are told to spend more.

At the same time, the United States benefits from access to one of the most strategically critical overseas facilities in the world, hosted under UK authority.

If defence solidarity is measured purely in GDP percentages, while strategic territorial access is excluded from the ledger, the accounting is incomplete.

The Hard Question: Could Britain Use Diego Garcia Alone?

If US–UK relations deteriorated significantly in future, could Britain meaningfully utilise Diego Garcia without American support?

The United Kingdom does not operate a long-range strategic bomber fleet. Carrier Strike Groups are limited and rotational. Sustained Indian Ocean logistics at scale depend heavily on alliance frameworks.

Strategic geography does not automatically translate into strategic leverage. It only does so when matched by credible capability and durable partnerships.

If the UK is committing nine-figure annual payments for a century, the financial and diplomatic framework deserves serious scrutiny.

The “Professional Circle” Narrative

It is true that Professor Philippe Sands represented Mauritius in litigation concerning the islands.¹⁰

But the ICJ advisory opinion and UN resolution materially altered the diplomatic environment regardless of personal networks.¹¹

Optics deserve scrutiny. Conspiracy does not replace analysis.

The Chagossian Dimension

Under BIOT law, entry without a permit remains unlawful.¹²

Removal orders are legally predictable. But legality does not resolve the deeper moral question of displacement.

The Closing Reality

We are told Diego Garcia is vital to the defence of the West. We are told alliances must endure. We are told to spend more.
Very well.
But alliances are not sustained by sentiment and strategic geography is not monetised by nostalgia. If Britain is to sign away sovereignty arrangements and commit billions over a century, the public deserves more than warm words about partnership. It deserves to know who benefits, who pays, and whether the balance is fair.

Anything less is not strategy.
It is drift with a price tag.

1
Treaty of Paris (30 May 1814), formal cession of Mauritius and its dependencies from France to Great Britain. See summary historical record, National Archives of Mauritius, ‘1814 – Treaty of Paris’. Available at: https://nationalarchives.govmu.org/nationalarchives/?cool_timeline=1814 (accessed 20 February 2026).
2
British Indian Ocean Territory Order 1965 (S.I. 1965/1920), made 8 November 1965, establishing the British Indian Ocean Territory. Available at: https://www.legislation.gov.uk/uksi/1965/1920/contents/made (accessed 20 February 2026).
3
European Court of Human Rights, Chagos Islanders v United Kingdom (Application no. 35622/04), decision of 11 December 2012. HUDOC database. Available at: https://hudoc.echr.coe.int/fre?i=001-115714 (accessed 20 February 2026).
4
International Court of Justice, Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965 (Advisory Opinion), I.C.J. Reports 2019, p. 95, 25 February 2019. Available at: https://icj-web.leman.un-icc.cloud/sites/default/files/case-related/169/169-20190225-ADV-01-00-EN.pdf (accessed 20 February 2026).
5
United Nations General Assembly Resolution 73/295, ‘Advisory opinion of the International Court of Justice on the legal consequences of the separation of the Chagos Archipelago from Mauritius in 1965’, adopted 22 May 2019. UN Doc A/RES/73/295. Available at: https://digitallibrary.un.org/record/3806313/files/A_RES_73_295-EN.pdf (accessed 20 February 2026).
6
UK Parliament, Written Question 57674, ‘Diego Garcia: USA’, answered 10 June 2025, confirming that no direct payment is made by the United States to the United Kingdom for use of Diego Garcia under the 1966 Exchange of Notes. Available at: https://questions-statements.parliament.uk/written-questions/detail/2025-06-05/57674 (accessed 20 February 2026).
7
Agreement between the Government of the United Kingdom of Great Britain and Northern Ireland and the Government of the Republic of Mauritius concerning the Chagos Archipelago including Diego Garcia (CS Mauritius No.1/2025), presented to Parliament May 2025. Available at: https://assets.publishing.service.gov.uk/media/682f25afc054883884bff42a/CS_Mauritius_1.2025_Agreement_Chagos_Diego_Garcia.pdf (accessed 20 February 2026).
8
UK Parliament, Written Question 57674, ‘Diego Garcia: USA’, answered 10 June 2025. Available at: https://questions-statements.parliament.uk/written-questions/detail/2025-06-05/57674 (accessed 20 February 2026).
9
North Atlantic Treaty Organization, ‘Wales Summit Declaration’, 5 September 2014, para 14, reaffirming commitment of Allies to aim to move towards spending 2% of GDP on defence within a decade. Available at: https://www.nato.int/en/about-us/official-texts-and-resources/official-texts/2014/09/05/wales-summit-declaration (accessed 20 February 2026).
10
International Court of Justice case records and related proceedings listing counsel for Mauritius in Chagos litigation. See ICJ Case 169 materials at: https://www.icj-cij.org/case/169 (accessed 20 February 2026).
11
International Court of Justice (2019) Advisory Opinion; UNGA Resolution 73/295 (2019).
12
UK Foreign, Commonwealth & Development Office, ‘BIOT laws and guidance for visitors’, GOV.UK. Available at: https://www.gov.uk/government/publications/biot-laws-and-guidance-for-visitors (accessed 20 February 2026).