Diego Garcia Military Base and British Indian Ocean Territory Bill

Lord Lilley Excerpts

Tuesday 4th November 2025 Lords Chamber

[Lord Lilley (Con)]

My Lords, it is a great privilege to follow the powerful speech by my noble friend Lady Foster of Aghadrumsee. I am tempted just to say “ditto” and sit down, but that is not the practice in this place, so I will focus on some aspects that differ from the focus that she gave. The importance she attached to the Chagossians enables me to be a bit briefer than I would otherwise have been.

I want to return to a powerful assertion that was made the first time this House considered a Statement on this subject, which was diluted a bit today in the defence put forward by the noble Minister. The original Statement by the Defence Secretary said

“without this deal—within weeks we could face losing legal rulings, and within just a few years the base would become inoperable”.—[Official Report, Commons, 22/5/25; col. 1284.]

What is the likelihood of us facing a legally binding ruling? If so, I ask the Minister, from which court is it likely to come?

First, as even the Foreign Office recognises, the opinion of the International Court of Justice was purely advisory, not binding. Secondly, it was based on UN General Assembly resolutions. Such resolutions are not legally binding, especially as they have not been endorsed by the Security Council. Thirdly, when the UK signed up to the International Court of Justice, our declaration specifically said that the Government of the UK excluded the jurisdiction of the International Court of Justice on

“any dispute with the government of any other country which is or has been a Member of the Commonwealth”,

as is Mauritius. Hence, the opinion of the ICJ was triply non-binding, and no future ruling of the ICJ on this dispute could be binding on us.

Ministers never mention these facts; either they are unaware of them, or they do not want us to know. Instead, they segue on to discussing the UN Convention on the Law of the Sea, as the noble Baroness did today, since that also has a tribunal. However, Article 298 of that treaty provides that states may “at any time” exclude “disputes concerning military activities”. Therefore, it is hard to see how the UNCLOS tribunal could reach a binding ruling which would impede our use of the base, still less do so in ways that the Defence Minister originally spelled out when he said:

“Rulings against us would mean we could not prevent hostile nations from setting up installations … on the outer islands … we could not guarantee the safe berth of our subs, patrol the waters around the base, control the airspace directly above or protect the integrity of our communications systems”.—[Official Report, Commons, 22/5/25; col. 1284.]


All that seems impossible to come from a tribunal which excludes, or where we can exclude, military matters.

These are not the only issues which the Government refuse to address. They never mention—even the Explanatory Memorandum on the agreement ignores it—the Pelindaba treaty, to which Mauritius is a signatory. It is signed by all countries counted as in the African region—and Mauritius is one—making Africa a nuclear-free zone. The treaty allows no reservations, at the time or subsequently, so it will apply to Diego Garcia, and it cannot be overridden by our treaty unless Mauritius resiles from the Pelindaba treaty. Do the Americans accept that that will mean that no nuclear weapons-carrying vessels or planes can use the base?

The agreement with Mauritius purportedly relates to completing the decolonisation of Mauritius. There are two relevant principles that have a bearing on the process of decolonisation. The first is the right to self-determination, and the second is the principle of territorial integrity. This agreement elevates the principle of territorial integrity above that of the right to self-determination.

It is bizarre that boundaries laid, and former administrative arrangements imposed on an area, by the colonial power should be treated as so sacrosanct, whereas the rights of the people who were displaced—many of whom would like to return or have the right to return—are to be ignored. It is even more bizarre given, as my noble friend Lord Callanan pointed out, the promise in the Labour Party manifesto that it would support the sovereignty, integrity and right to self-determination of peoples in the British Overseas Territories. I wait in the summing up to hear how the Government reconcile their promise made to the British people, and to the peoples of those territories, with what they are doing today.

Why are the Government ploughing ahead? Of course, they refer to the fact that negotiations began under the previous Government, although they were paused by the noble Lord, Lord Cameron. At the time they were paused, I found myself discussing this with a Foreign Office official, who I heard mention the agreement. I said, “Isn’t it good that these negotiations have been paused?” He obviously did not approve of the negotiations. He said, “Oh, it’ll make no difference; they’ll continue. It is the settled policy of the Foreign Office, whichever Government are in power, that we shall continue with this process to give away the sovereignty of them”.

[Lord Purvis of Tweed (LD)]

All the legal considerations that the noble Lord has outlined to the House, including those in the latter part of his remarks, pre-date November 2022, when the previous Government started negotiations to cede sovereignty. They took all his remarks into consideration, so why did they start negotiations to cede sovereignty?

[Lord Lilley (Con)]

The noble Lord is making a party-political point, as the Lib Dems always do. I am accepting that both parties are allowing themselves to be driven by the settled policy of the Foreign Office. We have to recognise that.

[Lord Purvis of Tweed (LD)]

It started in 2022.

[Lord Lilley (Con)]

Whenever it started, the settled policy of the Foreign Office will probably continue for another 22 years. Anyone who has been a Minister knows that every department has a settled policy that continues unless Ministers come along and determine to overthrow it.

[Lord Purvis of Tweed (LD)]

Earlier in 2022, the then Government’s view was that there would be no change to the sovereignty of Chagos. That was a Statement given to Parliament in early 2022. The policy changed under Liz Truss as Prime Minister and James Cleverly as Foreign Secretary to start negotiations to cede sovereignty. If there had been a settled will, it had been the one before the Government changed policy. It was the noble Lord’s Government who changed the policy.

[Lord Lilley (Con)]

Of course it was, but they allowed it to be changed from pressure from the Foreign Office. We can go into the archaeology of when this surfaced in the form of government policy and when it was internal, but I have no doubt that it was. Whenever I have spoken to Foreign Office officials, they have acknowledged that we are not bound by rulings of the court, nor are we likely to be, and nor are we bound by the obligations of any treaty, but they argue that Britain must none the less abide by even non-binding advisory opinions, since if we do not, how can we tell other countries that they must abide by international law? That is precisely the argument that was forwarded just now by the noble Lord, Lord Hannay.

It is touching that our diplomats believe that countries that might otherwise flout international obligations and rulings will change their ways and become law-abiding if they see us obeying rulings that we do not have to abide by and being purer than pure. I believe that the policy of the Foreign Office, and, above all, the policy of elected officials in charge of the Foreign Office, should be to pursue British interests and not to set about setting examples to other countries and virtue signalling. That is what this is doing, and it is weak for that reason. I hope that the House will in the weeks to come persuade the Government to abandon it.

--- Later in debate ---

[Lord Jay of Ewelme (CB)]

My Lords, it is always a pleasure to follow the noble Lord, Lord Bellingham, and particularly his very thoughtful speech today. I say at the outset that I support the Bill as a necessary consequence of the Chagos Islands agreement, which I also support.

I will not deal with the future of the Chagossians or environmental issues today, important though they both are. I will focus on security, but I think that both the British and Mauritian Governments will need to work hard to meet the justified demands of the Chagossian people.

I will not go over all the ground covered by the Minister in her opening speech, but I want to emphasise the importance of the base on Diego Garcia for our security and, more generally, for western security. A simple look at the map shows why it matters so much for our security, and for western security, in Asia, Africa and the Middle East, and why security of the base in the years ahead is so important.

For that reason, I continue to think—and, as I have said before in this House, I thought at the time—that it was absolutely right for the previous Government to start intensive negotiations with Mauritius, with the aim of ensuring

“the continued effective operation of the joint UK/US military base on Diego Garcia”;—[Official Report, Commons, 3/11/22; col. 27WS.]

that it was absolutely right for the then Foreign Secretary, the noble Lord, Lord Cameron, to decide, after examining the issue, to continue with the negotiations; and that it is absolutely right for the present Government to conclude them.

As I understand it—and I have listened carefully to the Minister—the agreement will provide us and the United States with the certainty we both need over the future of the military base on Diego Garcia for 99 years, plus another 40 years if we exercise our rights under the treaty. It does not surprise me that our Five Eyes partners—the United States, Canada, Australia and New Zealand—have welcomed the deal, recognising its importance for their and our security, nor that India, South Korea and the African Union have welcomed it too.

It would, of course, have been nice to have secured the deal without the cost. Some £101 million a year in today’s money is not cheap, and it would build a lot of hospitals. But surely the question is whether paying 0.2% of the defence budget is a price worth paying for the security it brings. I believe that it is.

Finally, it is worth considering the implications of our not agreeing a deal, of continuing with a contested relationship with Mauritius, the UN and the ICJ, and of ditching an agreement that we have reached with, and that has the support of, our Five Eyes partners. I know it is always risky to peer into the future, particularly given today’s uncertain world, but we can be pretty certain that the ICJ and UN General Assembly resolutions condemning us would continue. It is likely that they will be legally binding on us in the future. Could we just ignore that? Yes, we could, but in doing so, in these circumstances, we would be flouting international law. I believe—and I hope that the noble Lord, Lord Lilley, is listening—that the United Kingdom should be supporting and respecting international law, not flouting it. That has been, and should remain, our tradition, whether under a Conservative or a Labour Government.

May I also say to the noble Lords, Lord Lilley and Lord Blencathra—

[Lord Lilley (Con)]

The noble Lord said that we should pursue international law. Does he accept that we have, under the International Court of Justice, an opt-out for disputes between ourselves and Commonwealth countries—or was he going to mention that anyway?

[Lord Jay of Ewelme (CB)]

I was not going to mention that; I was making the simple point that respect for international law has been, and should remain, an extremely important part of British foreign policy.

I say this to the noble Lords, Lord Lilley and Lord Blencathra. When I was in the Foreign Office, serving under the late Lord Carrington and Lord Hurd, I was not conscious that there was a Foreign Office policy and not a government foreign policy. I have to say, I did not have the privilege of serving under the noble Lord, Lord Cameron.

The agreement with Mauritius and the treaty we are now considering respect international law, protect British and western security, have the support of our Five Eyes partners, India and others, and, in my view, unquestionably deserve our support.