The last words in the 83-page judgment delivered on Wednesday by the law lords in the case of the Chagossian islanders are those of Richard II: “It boots thee not to be compassionate; after our sentence plaining comes too late.”

Certainly, there is something of a Shakespearean tragedy in what has happened to the Chagossian islanders since they were evicted from their homes to make way for the US military base on Diego Garcia nearly 40 years ago. And certainly, there has been nothing compassionate about the behaviour of the British government in the treatment of them over the years.

The law lords have now ruled, by the narrowest of margins, that the Chagossians have no right to return. While there remains the possibility of taking the case to the European court of human rights, there is no disguising the fact that the lords’ ruling is a bitter blow to the islanders. They had arrived at the lords with the wind of two favourable judgments, from the divisional and appeal courts, in their sails – and some had even pledged that they would set off by sea before Christmas had the ruling gone their way.

It was in 2000 that the then foreign secretary, Robin Cook, made it clear that he supported the islanders’ case. It seemed only a matter of time before a small number of them returned to see if it was possible to recreate what was described by their lawyer, Richard Gifford, as “paradise lost”. Then came 9/11 and the insistence of the US that Diego Garcia, the island at the heart of the archipelago, was an essential “linchpin” in their security network, vital for the bombing missions on Afghanistan and, more recently, Iraq.

What the Americans had not said was that that Diego Garcia would also be used for “rendering” prisoners en route to Guantánamo Bay.

Almost everyone agrees that the Chagossians were shabbily treated, to say the least, but there does not seem to be anyone in government prepared to right the wrong. Robin Cook and that “ethical” foreign policy now seem as remote as the islands themselves.