UK-Mauritius Agreement on the Chagos Archipelago

Lord Hannay of Chiswick Excerpts

Monday 30th June 2025 Lords Chamber

[Lord Hannay of Chiswick (CB)]

My Lords, today’s debate is odd for two reasons, and that is the one point on which I think I agree with the introductory remarks of the noble Lord, Lord Callanan. First, had the outcome of last July’s general election been different, it is highly possible that the noble Lord, Lord Callanan, or one of his colleagues would have been standing at the Dispatch Box defending an agreement similar to the one we are debating now. How else can one construe the 11 rounds of negotiations that the Government of which he was a member conducted with the Government of Mauritius before that election following the ruling of the International Court of Justice and the overwhelming vote in the UN General Assembly that the UK should negotiate in this sense?

Secondly, the noble Lord, Lord Callanan, put down the wrecking Motion he has introduced calling for the agreement not to be ratified even though neither of the two committees examining the agreement—the International Agreements Committee, of which I have the honour to be a member, and the International Relations and Defence Committee—had even begun to take evidence on the text of the agreement, let alone put such evidence in the public domain. The reports of these two committees are now available to the House and they provide no—I repeat, no—justification for the Motion that the noble Lord has put before us. That surely demonstrates a contempt for the two committees, which is deplorable. Some will say, “Well, that’s just politics”, but it should not be so if the work of our committees is to be taken seriously by the House.

Now, that lacuna has been filled and our report and the evidence on which it is based have been published and are available to the House, as is the extremely valuable letter from the International Relations Committee. That it should have become available so late in the day is a matter for profound apology, but given the 21 working days we had to conduct our inquiry of quite a complex agreement, it was inevitable once the Government had already, at an earlier stage, turned down our request for an extension.

The committees heard the evidence of three distinguished international lawyers. While this evidence was not unanimous, two out of the three—Philippe Sands and Sir Christopher Greenwood—were very clear that the agreement reached was necessary if the UK was to avoid a legally binding finding at some point in the future in addition to the advisory opinion already rendered by the ICJ.

It was also particularly striking that Sir Christopher was so clear that it would be incompatible—I repeat, incompatible—with the policy expressed so frequently at the Dispatch Box by both the outgoing Government and the incoming one that the UK supports the rules-based international order, if the UK should then find it inconvenient to do so on this occasion. For what it is worth, that is my own opinion too. At a time when the rules-based order is under such severe attack, it would be especially damaging if one of its principal supporters were to choose opportunism over principle.

None of the evidence we received supported the view that has been expressed that this agreement is in any way analogous with, or undermines the legal basis for, the UK’s sovereignty over Gibraltar, the Falkland Islands and the sovereign base areas of Cyprus.

In conclusion, I would urge Members to vote against the Motion tabled by the noble Lord, Lord Callanan, and to take note of the report from the International Relations Committee, which clears the way for ratification of the agreement reported on. That is the course consistent with our national security interests and with our respect for international law.

Before concluding, I want to say how sorry I am to be speaking before the noble and learned Baroness, Lady Prentis, as I would have wished to congratulate her on her maiden speech. I am sorry also to be speaking before the noble Lord, Lord Boswell of Aynho. He was my boss on the European Union Committee for many years and a completely outstanding chairman of that committee, for whose work we should all express great gratitude today.

[Noble Lords]

Hear, hear.

--- Later in debate ---

[Lord Wolfson of Tredegar (Con)]

I am going to deal with the legal issues affecting this because the Government are saying to us, “We have no choice: we have to sign this because we have legal risk”. There is no point the noble Lord muttering from a sedentary position.

[Lord Hannay of Chiswick (CB)]

My Lords—

[Lord Wolfson of Tredegar (Con)]

I will finish the point and give way. This Government are trying to dress up a political decision as a legal decision. Now, of course, I am happy to give way.

[Lord Hannay of Chiswick (CB)]

I just wanted to ask the noble Lord to address the testimony given to the committee by Sir Christopher Greenwood, rather than having a lot of fun at the expense of Mr Philippe Sands.

[Lord Wolfson of Tredegar (Con)]

I have. Sir Christopher Greenwood made the point that we have legal risk. He is absolutely right: there is legal risk. But I am suggesting that we need to analyse that legal risk carefully.

There has been very little reference in the debate so far to the other evidence taken by the committee from Professor Ekins. Indeed, it is a shame that we have not been able to hear from the noble Lord, Professor Lord Verdirame, this afternoon because I would be very interested to hear his view on this issue. Ultimately, the committee heard from three lawyers. There is a difference of legal opinion on this issue, and that is because, ultimately, this is a political and not a legal decision.

Let me turn now to Article 4 of the treaty, which has not yet been raised. The premise of the agreement rests on the proposition that our interests will align with those of Mauritius for the next 99 years to the extent that there is no appreciable risk that Mauritius—and it has, of course, retained lawyers of the highest calibre—will seek to leverage the terms of the treaty for its own benefit. Merely to state that assumption is to show how unsafe it is.

I say 99 years; I was very surprised that the noble Lord, Lord McDonald, referred to 140 years. The ability in the treaty to extend it for 40 years is really not worth the paper it is not written on. There is simply no legal right to extend. There is an ability to negotiate, and the idea that there will be an extension, absent perhaps another huge payment of money, really is for the birds.

Article 4 provides:

“Each Party agrees to ensure that in the implementation and application of this Agreement, including activities in relation to the Base, there shall be compliance with international law”.


No court or body is appointed to deal with that issue. If Mauritius, advised by its eminent lawyers, took the view that UK or US operations out of Diego Garcia are not in accordance with international law, then it could allege the UK was in breach. That would not entitle Mauritius to terminate the treaty—the rights of termination are limited in Article 15—but it would entitle it to take countermeasures which would otherwise be prohibited under the treaty, such as allowing the presence of armed forces of other countries or constructing installations elsewhere on the islands that might adversely affect the security of Diego Gracia. Let us be clear: if Mauritius took that action, there would be nothing that we could do and we would not be entitled to stop paying the sums that we have promised to pay under the treaty.

There is a similar legal risk under Annexe 1. It was mentioned earlier that we have to inform Mauritius about the use of force originating from the base at Diego Garcia “expeditiously”. I have three questions for the Minister in this regard. First, my understanding is that the UK’s position is that this provision requires notice only after an operation is launched. Is that correct? Secondly, assuming that it is only after an operation is launched, what do we consider “expeditiously” means? Does it mean that we have to inform Mauritius as soon as the planes take off, or can we deliberately decide to delay informing it, even though we could inform it, until the operation has been completed? Thirdly, whatever our interpretation of that word might be, have we agreed that interpretation with Mauritius? If we have not, I can give the Minister some free legal advice: all of this is very ripe for a further dispute, which would likely result in Mauritius not abiding by its obligations under the treaty.