I wonder whether they thought of taking a leaf out of the US's book and moving the detainees outside of Britain proper. The few remaining fragments of the British Empire could lend themselves to small-scale, high-security penal colonies, sufficiently inaccessible to add to their security. Possible locations for a British Guantanamo could include:
Of course, Britain doesn't have as free a hand with extraterritorial penal facilities as the US does, because of that meddlesome European Convention on Human Rights (which, a court has found, even applies to British troops in Iraq), which could complicate these options. Though if, as claimed, the detainees are foreign nationals with no right to residency in Britain, they could possibly be handed off to a compliant foreign government to look after. The US would be a good choice (they have the facilities, after all), though other members of the Coalition of Willing could be looked at. Australia, for example, could repurpose some of its extraterritorial refugee holding centres.
In fact, pick any poor pacific nation that is about to sink and has had all it's natural resources plundered.
Well, Nauru would involve the additional hassle of negotiating with a nominally sovereign government. Whereas, the examples cited above are administered by bureaucrats in London. (In fact, Ascension Island, best known as a US signals-intelligence post against African Marxism, is nominally run by the BBC.)
"The few remaining fragments of the British Empire could lend themselves to small-scale, high-security penal colonies, sufficiently inaccessible to add to their security"
Like Nauru, for instance.