God bless Donald Trump. He may be mad, bad and dangerous to know, but on one issue he is triumphantly right.

Having seesawed over several months, the US President opposes the British Government’s plan to give the Chagos Islands to Mauritius. Sir Keir Starmer had agreed to pay at least £35 billion for a 99-year lease on the main island, Diego Garcia, which we already own.

The Americans maintain a crucially important Indian Ocean base on Diego Garcia. Trump can see that a lease isn’t a solid arrangement. It could be rescinded or varied by Mauritius, an ally of China.

For Starmer, Trump’s veto (which he is entitled to exercise under a 50-year-old Anglo-American agreement) represents the biggest humiliation of his error-strewn prime ministership.

Starmer was determined to do the deal, which the Government bizarrely described as ‘vital’ to British interests. He tried to sweet-talk Trump while concealing the enormous cost from Parliament.

But during America’s onslaught on Iran the President has grown increasingly irritated with the occupant of No 10. According to Lord McDonald, a former head of the Foreign Office, the deal has been put ‘in the deep freeze’.

Wonderful news. The trouble is that what is frozen can be defrosted. We shouldn’t assume that Starmer’s foolish, wildly unpopular and ruinously expensive agreement with Mauritius is permanently dead.

The mercurial Donald Trump might change his mind again, and decide that America can live with a 99-year arrangement on Diego Garcia after all. In that case, Starmer would instantly retrieve the deal from the deep freeze.

Meanwhile an incandescent Mauritian government is certain to bring legal action against Britain to get its hands on the money Starmer so recklessly promised.

It had planned to use the proceeds to remove 80 per cent of its population from income tax, while eyeing up lucrative contracts with India to look for minerals in the Chagos Islands.

A wholly misguided bonanza has been abruptly withdrawn. Starmer – or his successor as prime minister – could buckle as the Mauritians mount their legal case. I wouldn’t rule out the Government offering hefty compensation.

Why? That is the question. Why was Starmer determined to pay so much money for islands legally acquired by a Labour government in 1965 for £3 million when Mauritius became independent?

The answer to that question takes us deep into the mind of modern Labour. What we find is incredible naivety combined with moral smugness and a reverence for international law. Add a penchant for wasting public money and – hey presto – you have the disastrous deal Starmer proposed.

In this he was helped by his old friend, Attorney General Lord Hermer, who reaches for his well-thumbed books on international law before considering British interests – if he does so at all.

Starmer was also aided by national security adviser Jonathan Powell who, like Starmer and Hermer, believes that anything the British state did before the emergence of New Labour in 1997 should be automatically questioned.

The views they hold – that the British Empire was always at fault and that colonies such as Mauritius were invariably oppressed – are shared by thousands of bien pensant people in the choicer parts of North London. They are ubiquitous in the Foreign Office itself.

A sensible person would get out a map and observe that the Chagos Islands are nearly 1,300 miles from Mauritius. Such a person with a knowledge of history would also know that the islands never belonged to Mauritius, and were lumped together with the distant colony for administrative purposes.

And a sensible person wouldn’t cave in and accept the verdict of an international court that was at least partly motivated by anti-colonial sentiments.

This is what happened in 2019, when the International Court of Justice in the Hague ruled by 13 votes to one that the British ‘occupation’ of the Chagos Islands was illegal.

The President of the court was a Somali judge. His deputy was Chinese. Both countries are of course famed for the independence of their judiciary, while their respect for the rule of law is legendary.

There was a Russian judge on the panel who voted that Britain should give up the Chagos Islands. Included among those who took the same view were judges from Jamaica, Uganda, Morocco and Brazil – countries which, as former colonies, are liable to side with Mauritius.

By an amusing quirk, a judge from Lebanon, Nawaf Salam, is now prime minister of that country, currently being bombed by Israel. No doubt he was a distinguished jurist but perhaps not one who would rush to defend Britain, a former colonial power. The sole judge who did so was American.

Our rulers could have politely questioned the objectivity of this court. They could have in any case disregarded its judgment, which was merely advisory.

Instead, guided by the Foreign Office, which is ever eager to bend the knee, they took the court seriously. First the Tories danced around the ruling in a friendly way, though without accepting it. Then arch chump Keir Starmer blundered onto the stage, and the rest is history.

The aforementioned Lord McDonald of the Foreign Office told the BBC on Saturday that ‘the UK has always defined itself as a country which respects, upholds international law’. But what if that law flies in the face of common sense and is promulgated by a biased court?

There is another aspect to this case which may be even more shaming – namely the complete reluctance of either the Mauritian or British governments to show any concern for the original inhabitants of the Chagos Islands.

After the British struck a deal with Mauritius in the 1960s they did one bad thing. About 1,500 Chagossians were removed from their homeland. Many of their descendants live in Britain, and some of them would like to return to the islands.

This is feasible in the outer islands, according to informed studies, though not on Diego Garcia itself. But neither the British nor Mauritian governments have shown the slightest interest in repatriating those Chagossians who do want to go back. To his credit, Nigel Farage has championed their cause.

Starmer is keen to be seen doing the right thing, which in his view is tearing up a colonial-era agreement and showering the Mauritian government (which, by the way, has in recent times been corrupt) with untold billions of pounds of our money.

But actually he is interested only in fulfilling what he believes are the dictates of international law. As so often, he is up a gumtree. The only obligation Britain has is a moral one, which is to help Chagossians return to their islands.

When the chips are down Starmer doesn’t care – or he doesn’t care about the right things. He wants to side with the anti-colonial brigade in the belief that such an association makes him look virtuous. Maybe around the dinner tables of North London, but not throughout the British nation.

For now, at least, Trump has scuppered his plan. Let us rejoice about that. It is a huge blow to Starmer. But he will still try to pull off this foolish, damaging deal if he can. Take it out of the deep freeze, and dump it for ever in the bin.