The Chagos Treaty is still not ratified by passing a UK law to bring it into effect. The Lords is unhappy with it and it is subject to a legal case against. The government failed to consult Chagosians properly who do not it given away to Mauritius.
The government is short of money so offering an annual subsidy to Mauritius to take over the islands is mad. This is valuable territory.
The government needs to reflect on President Trump’s new world strategy. That makes clear it is in the US and the Western alliance’s interest to keep open the shipping lanes in Asia and to preserve the current status of Taiwan. The Chagos joint US UK base is critical to defending open navigation into the South China Sea.
Giving away the freehold means Mauritius, friend of China could grant fishing rights in currently environmentally protected waters. Chinese vessels could come close to the base. People could settle on other islands close to Diego Garcia, creating tensions with the base.
At the moment this remote island base is well away from settlements and from prying eyes. Changing it could be expensive and dangerous. There is no need to. Please government think again.