All at sea - Sir Keir’s Chagos Treaty sinks under legal cross examination
'Worst deal in history’ must now be confined there, as Government admits our legal argument is correct after all
Montage © Facts4EU.Org 2025
Facts4EU vindicated, after formal written response from Foreign Office torpedoes central pillar of Government's case
Sir Keir Starmer's Government has been forced in writing to admit that our legal argument against the hugely expensive giveaway of the Chagos Islands is correct after all. Put simply, in just 24 words the Government's case for the surrender of Britain's most important strategic base in the World has been swept away.
On Thursday last week, the Parliamentary Under-Secretary of State for the Indo-Pacific, Seema Malhotra MP, gave a written response to a Parliamentary Question in which she confirmed that Britain's opt-out of the international law of the sea for military bases is indeed in force. This had been the main pillar of the Government's case that the UK’s base at Diego Garcia, shared with the US, was under threat of legal action “within weeks”
It is almost one year since Brexit Facts4EU first revealed the existence of an opt-out and now, finally, this has been admitted in writing by the Government.
Here is the exchange and below we explain the significance
© Crown / Parliament - click to enlarge
[Source(s): Hansard ]
Without its legal case, Sir Keir's argument to denude British and US naval power in the Indo-Pacific must go the way of its aborted local election ban
Our update today on what has been 12 months' work supplies the crucial element in this definitive summary of Sir Keir's and David Lammy's disastrous foray into the uncharted waters (for them) of post-colonial geo-politics. Without this, the Government simply has no case.
It conclusively destroys the Government’s Treaty with Mauritius over the Chagos Archipelago in the Indian Ocean and the surrender of the sovereignty of the United Kingdom over it, including the strategically-vital military base of Diego Garcia.
This summary report adds the latest evidence from last Thursday to our last summary of a five-hour debate which took place in the House of Commons on Tuesday 09 September 2025, during which the Government gave its reasons for the necessity of its Treaty with Mauritius and in which opposing Members argued against each and every one.
This whole justification now no longer exists so the Treaty must be abandoned.
A victory for all Brexit Facts4EU readers who supported us over the past year
At this point we would like to thank those Facts4EU.Org readers who donated towards our work in fighting this ignominious treaty during the last 12 months. It was the hours of research which we started in January 2025 which has brought things to this point.
The Government has yet to capitulate but capitulate it now must, after admitting the central pillar of its justification for this act of treachery is actually built on sand, as we wrote in September, and must now go the way of the local election ban and all the other U-turns forced upon this Government.
Donors, we are almost there and you may take a small bow.
Please now see us over the line as we fight to ensure this Treaty is in fact now to be abandoned.
The Facts4EU team gratefully acknowledges the assistance and advice of Stand for Our Sovereignty, The Campaign for an Independent Britain (CIBUK), the UK Fisheries Campaign, and a number of the country’s most respected senior lawyers and politicians.
We also tip our hats to Claire Bullivant and her team at GB-PAC for their unstinting fight on many fronts.
Our Chairman would also like to thank the First Minister of the Chagossian Government in Exile, Mr Misley Mandarin, for his invaluable help during this process.
The Government’s case ‘in a nutshell’
The Government’s case was that the existence of the UK’s base at Diego Garciawas under threat of legal action “within weeks” and that:
“A binding judgment against the UK seemed inevitable.”
- David Lammy, then Foreign Secretary, House of Commons, 07 Oct 2024
This would make the base “inoperable”, so a Treaty was signed which guarantees the use of the base for a further 99 years, unhindered, after which it could supposedly be renewed. Although signed, the Treaty still has not been ratified by Parliament and so may now be withdrawn.
The Opposition’s case ‘in a nutshell’
The Official Opposition say the Government has produced no evidence to substantiate its claim, or where they have it is erroneous. There have been no legally binding judgements against the UK and nor are there likely to be. The deal involves the transfer of £35 billion to the government of Mauritius, an ally of China, Russia and Iran. The costs have been wildly understated by the Government.
“In the mid-1960s we paid Mauritius for the freehold and to cede all future claims over sovereignty. This new leasehold deal is the worst in history and Reform will rip it up.”
- Richard Tice MP, Deputy Leader, Reform UK, speaking to Facts4EU.Org and Stand for Our Sovereignty, 10 Sept 2025
The conditions include notification to the Mauritian government of military actions, and approvals needed for the construction of facilities. Mauritius is party to an African nuclear treaty forbidding the presence of nuclear weapons. At the end of the term – if the Mauritians do not renege on its terms before that – China or Russia would be able to outbid the UK and take control of the islands and the base.
A democratic desert: If passed, Article V of the Bill allows the Government to change the terms at will, without recourse to Parliament.
Why should you care about an island so far away?
The importance of the base cannot be overstated. The joint UK-US base on Diego Garcia has played a vital role in defending the UK and its allies for over 50 years. The base plays a key role in operations that support UK forces and our allies across the Middle East, east Africa and south Asia. Its deep-water port, airfield, and advanced communications and surveillance capabilities, give the UK and our allies crucial strategic capabilities, which have played a key role in missions to disrupt high-value terrorists, including Islamic State threats to the United Kingdom.
These are not our words. They are produced verbatim from the Hansard record of the Government Minister, Luke Pollard, as he set out the reasons for the Government’s Treaty in Parliamewnt.
The Minister continued on the legal necessity for action
“But the base on Diego Garcia was under threat. Had we not signed the treaty, we could have faced further legal rulings against us within weeks, because the negotiations begun by the Conservatives had been stayed. Further legal rulings might have included arbitrary proceedings against the UK under annex 7 of the UN convention on the law of the sea, known as UNCLOS.”
“A judgement from such a tribunal would be legally binding on the UK. It would impact on our ability to protect the electromagnetic spectrum from interference, and impair our ability to ensure access to the base by air and sea, to patrol the maritime area around the base and to support the base’s critical national security functions.”
“Courts and international bodies were already making decisions that undermined our position. Others would have followed suit, taking us down a path towards making the base inoperable. This Government will not allow that to happen.”
The reasons why this Treaty must not proceed
The whole legal justification was built on sand
Legal summary: “It is not just that the Government are not answering the questions; it is that when they do answer the questions, they undermine their own argument. It is worse than we thought. We are not getting clarity from the Government about what would be the legal judgement that they themselves have relied on as almost the entire basis for their actions, and this really matters.” – Sir Jeremy Wright MP, former Attorney General.
The Government have cited four sources of legal cases against the UK: UNCLOS (law of the sea), the ICJ (International Court of Justice), ITU (use of radio spectrum), and the UN generally. In none of these is a binding judgment against the UK justified or possible.
1.1 UNCLOS – “…article 298(1)(a) and (b) give us specific exemptions from UNCLOS judgements across all those areas. That is relevant to the UK in ‘disputes concerning military activities…by government vessels and aircraft…in non-commercial service, and disputes concerning law enforcement activities’” – Sir Iain Duncan Smith MP.
It is the above that was the Government's main pillar for its legal argument. And it is this which they have now admitted does not exist.
1.2 ICJ – The International Court of Justice issued an advisory opinion on sovereignty over the Chagos Islands and Diego Garcia. On 22 February 2017 the UK was exempted from “any compulsory jurisdiction in relation to any dispute with a Government of any other country which is or has been a Member of the Commonwealth. That involves and includes Mauritius, so any dispute with Mauritius before the ICJ could not result in a binding judgment against the United Kingdom. That point has been put to Ministers and, as far as I know, they have not dissented from that analysis.” - Sir Jeremy Wright, Attorney General at the time.
1.3 ITU – The International Telecommunications Union cannot make any binding judgements against the UK because the spectrum decisions are down to individual countries. “Is my right hon. and learned Friend aware of the written answer from the Government on 7 February this year: ‘Individual countries, not the ITU, make their own sovereign spectrum assignments in accordance with the Radio Regulations. The ITU has no legal authority over these assignments regardless of the country’s civilian or military classification of spectrum’?” - Sir John Whittingdale MP.
1.4 The UN generally – The Government has only vaguely mentioned this in passing but we will deal with it. With the majority of countries being smaller and poorer than the UK and other western countries such as the U.S. and many of those of the EU, votes routinely go in favour of a smaller country such as Mauritius. These are usually ignored and in any event the UK is a one of the P5 permanent members of the Security Council and can and does use its absolute veto.
1.5 ‘Finally, a cascade’ – A central plank of the Government’s case is that there would somehow be a cascade of binding legal judgments against the UK, stemming from the non-binding judgment of the ICJ. It is self-evident that any judgment from a different international body relying on the non-binding ICJ judgment would have no basis in law.
“The Government say they abide by the law. Given the opt-out that we had, the original judgment was specifically not found in law, because we did not allow the ICJ to rule on Commonwealth issues. The question is a matter of law, so if the Minister is suggesting to the House that other actions would have taken place, they would the above have been unlawful. In what world was it necessary to block off those by assuming that this was law? It was not lawful.”
- The Rt Hon Sir Iain Duncan Smith MP, former Leader, Conservative Party, 09 Sept 2025
Despite continual requests, the Government has been unable to cite one single example of a binding judgement against the UK, or the realistic possibility of one. Nevertheless, it has been making the claim since last year that the UK is under imminent threat “within weeks”. This is simply not the case.
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Given that the Government has rested its case on the threat of “further legal rulings against us within weeks”, and this has proven to be false, the Government’s justification for its Treaty has been unequivocally destroyed.
Crucially, the Government itself has now admitted - in writing - that its principal legal pillar for being forced to take action NO LONGER EXISTS.
Observations
The debate last September began at 1.26pm on Tuesday 09 September 2025 and the first Division took place at 6.42pm. In preparing the above, the Facts4EU team and colleagues in our associated organisations such as Stand for our Sovereignty read all 51,000 words of the official Hansard transcript.
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[ Sources: House of Commons Hansard | UNCLOS Treaty | ICJ | ITU | Our legal advisors] Politicians and journalists can contact us for details, as ever.
Brexit Facts4EU.Org, Tues 17 February 2026
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