Diego Garcia Military Base and British Indian Ocean Territory Bill

Earl of Leicester Excerpts

Report stage
Monday 5th January 2026 Lords Chamber

[Lord Lilley (Con)]

My Lords, I apologise to the House for being absent for my amendments in the first group. I am grateful to my noble friend Lord Hannan for moving them on my behalf with, I am sure, greater elegance than I would have been able to bring. Were I a believer in conspiracy theories, I would imagine that President Macron and Prime Minister Starmer had got together to prevent me from returning to this House, but I am sure that they both have more serious issues, given their lack of popularity in their respective countries, than dealing with me.

My Amendment 14 seeks for the Government to negotiate guarantees from the Government of Mauritius that Mauritius will not enforce its duties under the Pelindaba treaty on the base of Diego Garcia and to ensure that, if it were to do so, the sovereignty of the base would revert to the UK. The Pelindaba treaty seems pretty clear that it excludes the use of any part of any African country. Mauritius counts itself as an African country. When it takes sovereignty of the Chagos Archipelago, which we count as part of Africa, it will preclude any of those countries from having any nuclear weapons or armaments on that territory. It would therefore be very difficult, on a simple reading of the Pelindaba treaty, for us to use that for our nuclear submarines or for any aircraft carrying nuclear weapons.

The Mauritius treaty, as it is written, says:

“Each party confirms that none of its existing international obligations or arrangements now in force or effect between it and any third party is in conflict with the provisions of this Agreement”.


If that means that the parties to the agreement intend to ignore any other agreements that they have that may conflict with this, that is all right with me, but the trouble is that it then goes on to say,

“nothing in this Agreement shall affect the status of existing international obligations or arrangements except as expressly provided for in this Agreement”.

That would appear to suggest that nothing in this agreement will override the Pelindaba treaty unless it is expressly stated in this agreement. It is not expressly stated.

I have every confidence in the two Ministers’ patriotism and that they would put the defence of this country manifestly above other minor considerations. I am sure that if it was left to them, we could rely on all this, and I could sit down and not pursue the argument further. But we know that this Government say that their highest priority is international law. If they are now saying that they are prepared to ignore legal agreements and enter into agreements with countries expressly on the basis that they ignore international agreements into which they have entered, we are in a difficult position. I notice the noble and learned Lord, Lord Hermer, is in his place. Perhaps he has come especially to give us assurances that he will not, in this instance, express the supremacy of international law, and that ultimately the sovereignty and independence of this country, its military defence and its alliance with the United States take priority over those matters. Now, if we can have that assurance, that is fine by me.

I appreciate that here we are dealing with very sensitive matters, and I do not expect the Minister to go into fine detail, but I would like the Government to give me greater assurance than I get from reading the treaty that the Pelindaba treaty is not going, at some future stage, to be cited by Mauritius as a reason why we cannot use nuclear-powered vessels or nuclear-equipped weapons, armaments and aircraft from the base. Unless we have that assurance, we must be rather worried.

[The Earl of Leicester (Con)]

My Lords, I, too, was detained in France so I was not able to speak to my first amendment, Amendment 20, but I shall speak to my Amendment 21 and I support all the others in this group. Amendment 21 basically seeks to ensure that the Secretary of State consults the UK’s AUKUS partners on the transfer of the sovereignty of the Diego Garcia base and that we get the written approval of the Governments of Australia and the USA and the opinions of the senior naval staff of all three partners.

AUKUS is central to the strategic defence review. Secretary of State John Healey states in the foreword to the SDR that

“the AUKUS programme … will allow us to grow our nuclear-powered attack submarine fleet to up to 12. This will reinforce our Continuous at Sea Deterrent … and position the UK to deliver the AUKUS partnership with the US and Australia”.

There have been a number of notable naval critics; indeed, one of them, the noble Lord, Admiral Lord West of Spithead, on the Government’s Benches, a former First Sea Lord and Security Minister, warned:

“The Government may genuinely believe that the base’s long-term future is ‘more secure under the agreement than without it’. But … How can the base–which serves as an indispensable naval, air, and intelligence asset–be more secure under the sovereignty of another nation, rather than under our own?”


In November last year, retired Rear-Admiral Chris Parry criticised the Government’s deal to transfer sovereignty of the Chagos to Mauritius. He described the decision as “the biggest strategic mistake” he has seen in his lifetime. In February last year, Commander Peters, a retired Royal Navy officer who led British forces at the joint UK-US base on Diego Garcia said that the base was currently “easily defended”, but:

“If the outer islands are under Mauritian control, China could quite happily start redeveloping them and installing all sorts of spying equipment that I think would affect the security of Diego Garcia”.

--- Later in debate ---

[The Minister of State, Ministry of Defence (Lord Coaker) (Lab)]

My Lords, it is a pleasure to get up for the first time on Report and address your Lordships on this important group dealing with security matters. I will try to come to some of the points that have been raised.

I will come to the point about the letter that the noble Baroness raised, but I will start with the challenge that she put at the end to explain how the Government are dealing with the position on the treaty from a security point of view. This answers some of the questions that have been asked, not least by the noble Lord, Lord Morrow, and I will not go into some of the operational points that have been made by him and others. However, on the security matters, I can say that if your Lordships look at the expressions of support for the security aspects of this treaty, all our major international allies and partners have supported the security arrangements. That is a fairly significant point for us to make and a fairly important point for the House to recognise.

To answer the noble Baroness, the noble Lord, Lord Morrow, and the noble Earl, Lord Leicester: President Trump expressed support for the Diego Garcia arrangements within the treaty. US Secretary Hegseth said:

“Diego Garcia is a vital military base for the US. The UK’s (very important) deal with Mauritius secures the operational capabilities of the base and key US national security interests in the region. We are confident the base is protected for many years ahead”.


That was not me but the US.

[The Earl of Leicester (Con)]

What is the US paying Britain for the lease? It is pretty clear why the Americans are supporting this: they are not having to shell out £34 billion.

[Lord Coaker (Lab)]

The US pays for the operations at the base and has done for many years. I say to the noble Earl that it is a fairly important policy that the Government have secured this to ensure the security of the base over the coming decades. I will come to AUKUS in a minute, but the noble Earl, the noble Lord, Lord Morrow, and other noble Lords have asked in their amendments how the treaty arrangements protect the security of the base. All I am doing is reading out what our crucial allies are saying about it. I am saying what they are saying about it. They are paying for the operation of the base. We have secured the future of the base, and they are supporting it. Secretary Rubio came out and supported the base as well.

People ask me how we have secured it—this is the challenge the noble Baroness put to me—and how we have ensured that we have secured the future of the base. We have secured it by ensuring that our major allies support it. I can only imagine what the noble Earl would say if I could not read out quotes from the US supporting what we are doing. The Five Eyes have all supported it. Of the AUKUS partners, Australia supports it as well as the US. Canada, Japan, Korea and India have supported it. I think that is an important position for the Government to be in. That is the context within which all the amendments should be considered.

I do not question the desire of noble Lords in their amendments to challenge the Government and to understand how effectively we have done that. All I am arguing before your Lordships is that, in the context of the treaty, the future of the base is secured. That is a fairly important statement for the Government to be able to make. I will come to the Pelindaba treaty when I come to the amendment from the noble Lord, Lord Lilley, and address the specifics that the noble Baroness raised.

Amendment 8 tabled by the noble Lord, Lord Callanan, requests a statement from the Secretary of State on base security. The treaty has robust security provisions to protect the base, including full operational control of Diego Garcia, full UK control over the presence of foreign security forces across the archipelago and an effective veto over any construction or development that risks undermining, prejudicing or otherwise interfering with the long-term, secure and effective operation of the base on Diego Garcia. Claims that Mauritius is an unreliable partner and one that cannot be trusted are unfounded. Mauritius is a member of the Commonwealth and a westward-facing country with shared democratic values. Mauritius ranks among the top African nations in governance, human development and innovation. It is a full democracy, a regional leader in human rights and a trusted partner in upholding the rules-based international order, ranking second out of 54 African countries in the Mo Ibrahim Index of African Governance.

I thank the noble Lord, Lord Lilley, for tabling Amendment 14 and the noble Baroness, Lady Goldie, for supporting him. The noble Baroness asked me—I hope this helps the noble Lord, Lord Lilley, as well; I always try to be helpful, as noble Lords know—to ask my officials to draft a letter between now and Third Reading. Of course I will do that. I cannot guarantee that the content will necessarily be everything that the noble Baroness or the noble Lord want, but asking for a letter is a perfectly reasonable request. That will be done, and I will place a copy of it in the Library so that it is available to all noble Lords to consider as we move towards Third Reading.

Regarding the amendment tabled by the noble Lord, Lord Lilley, he knows—he has been a senior Minister and has a distinguished former Prime Minister sitting next to him—that it is very difficult to answer some of the specific questions that noble Lords have posed about certain capabilities. The noble Baroness, Lady Goldie, recognised that we cannot talk about it. I will say what I can. Amendment 14 tabled by the noble Lord, Lord Lilley, would require guarantees

“that Mauritius will not enforce its duties under the Pelindaba Treaty on the Base”

and that sovereignty would revert to the UK if it did. As I said in Committee, the Governments of the UK and Mauritius are both satisfied that the Diego Garcia treaty is compatible with their existing obligations under applicable international law. The UK will ensure that all operations on Diego Garcia comply with its existing obligations. The UK is not a party to the Pelindaba treaty, although it is a party to Protocols I and II. The treaty and the Bill will allow the base to operate as it always has. It will not reduce our ability to deploy the full range of advanced military capabilities to and from Diego Garcia in any way.