Luke Evans: The Chagos deal is not just flawed, but dangerous

Dr Luke Evans is shadow minister for health and social care.

In Monty Python and the Holy Grail, the Black Knight has his arms and legs hacked off, yet still insists it is “just a flesh wound”. Watching Ministers defend the Chagos deal now feels much the same.

Every time a Minister is asked a straight question, they dodge it. Another limb gone. Another “tis but a scratch”. MPs ask what happens if the United States refuses to agree. No answer. MPs ask how nuclear treaties affect our most sensitive military base. No answer. MPs ask who really controls Diego Garcia once sovereignty is handed away. Still no answer.

Instead of clarity, the Labour Government shouts political “gamesmanship”. That charge collapses on contact with reality. This is not political theatre. It is Parliament doing its job.

When ministers cannot explain the consequences of giving away British territory, the problem is not the questions. The problem is the deal.

The Government insists that the proposed Chagos Islands deal is necessary, settled and legally sound. Yet each time Parliament asks simple, reasonable questions, Ministers struggle to give clear answers. That alone should give the country pause. But the deeper one looks, the more serious the problems become. This deal is not merely imperfect. It risks undermining Britain’s nuclear deterrent, our alliance with the United States, and our credibility at a time of global instability.

It should be scrapped.

At the heart of the issue is sovereignty. Handing the Chagos Islands away is not an abstract legal exercise. Sovereignty determines which laws apply, which treaties bind, and who ultimately controls what happens on strategically vital territory. Nowhere is that more consequential than Diego Garcia a crucial military base in the Indopacific.

One unanswered question has loomed over this debate from the start. Can Britain unilaterally transfer sovereignty over the Chagos Islands without American agreement under the 1966 UK–US Exchange of Notes?

Ministers have explained the process repeatedly, but they have never answered the crucial point: What happens if the United States does not agree to amend that agreement? If the answer is that the deal collapses, ministers should say so. If the answer is something else, they should explain it. Silence on this point is not reassurance. It is a warning sign.

Yet even that is not the most troubling issue. The most serious problem lies in the interaction between the proposed treaty and the Treaty of Pelindaba, the African nuclear-weapon-free zone treaty, to which Mauritius is a signatory.

Pelindaba is explicit. It prohibits the stationing, storage and possession of nuclear explosive devices on the territory of signatory states. It goes further, committing those states not to assist or encourage such activity. Therefore, logic suggests that if we transfer sovereignty of Chagos to Mauritius, and we lease the UK-US base as proposed, then even having nuclear weapons pass through the base would place Mauritius in breach of Pelindaba.

There is a limited carve-out. A signatory state may, at its discretion, permit visits by foreign ships or aircraft. That means transit could, in theory, be allowed. But storage cannot. Permanent basing of nuclear weapons would be prohibited. Even transit would require explicit permission each and every time.

This matters enormously. The credibility of the UK’s nuclear deterrent, and the deterrent posture of our closest ally, relies on ambiguity and assured access. A situation in which nuclear-armed vessels or aircraft require case-by-case permission from another sovereign state is not a technical inconvenience. It is a strategic vulnerability.

When Ministers were asked directly how the proposed treaty interacts with Pelindaba, they could not or would not answer. Instead, they pointed to language in the draft agreement referring to “weapons and hazardous materials”. That wording notably does not mention nuclear weapons at all. Given the legal specificity of Pelindaba, that omission is not trivial. It is profound.

At a time when global security is increasingly fragile, when deterrence and allied trust matter more than ever, the idea that Britain would voluntarily place constraints around the use or credibility of its nuclear deterrent should alarm everyone, regardless of their Party.

This is not the only unresolved legal issue. The Government continues to invoke a non-binding advisory opinion from the International Court of Justice, while remaining vague about which court, precisely, could enforce a judgment against the UK. Other international bodies regularly cited by Ministers, from maritime to telecommunications forums, explicitly lack jurisdiction over sovereignty. There is also a clear Commonwealth opt-out that has never been properly addressed.

If the legal risk is real, Ministers should explain where it lies. If it is not, they should stop hiding behind it.

The financial case is equally troubling. The Government cites a cost of £3.4 billion based on net present value calculations. However, Government actuaries put the figure closer to £34 billion in nominal terms. Net present value may have its place in domestic spending decisions, but using it to justify the permanent transfer of sovereign territory over nearly a century stretches credibility. No one can seriously claim to model political, economic and security risk over 99 years with that level of confidence.

Then there is the environment. The UK currently enforces protections in the region. Mauritius does not possess a navy capable of doing so. History suggests fishing rights, not conservation, will come first. Ministers have yet to explain how environmental safeguards would be upheld in practice.

Each of these issues on its own would justify delay. Taken together, they point to something more serious. This deal has not been thought through. It rests on legal ambiguity, financial sleight of hand and strategic optimism at a moment when realism is required.

Parliament is not asking for theatrics. It is asking for answers. Until the Government can clearly explain how this deal does not weaken our deterrent, does not undermine our alliance with the United States, does not expose us to legal risk, and does not leave Britain poorer and less secure, it has no mandate to proceed.

In truth, that threshold has already been crossed. This is not a deal that can be fixed with better drafting or warmer words. It is a bad idea at its core. For the sake of Britain’s security and credibility, it should be scrapped entirely.