Sir Julian Lewis: I think there is a further twist, because the Pelindaba treaty not only prohibits the storing of nuclear weapons on the territory of Mauritius, which the Chagos islands would become, but requires an inspection regime. I understand that the country that would carry out the inspection is South Africa, which is somewhat closer to China and Russia – particularly where naval co-operation is concerned – than it is to America or the United Kingdom.

[Sir Iain Duncan Smith: My right hon. Friend is absolutely right, as he normally is. The reality is that the treaty to which he refers is very clear that its signatories cannot modify it; they must categorically agree not to have nuclear weapons on their territory. We are in the business of giving that territorial right to Mauritius, so there is no question but that the treaty will apply to Chagos. …]