The Prime Minister had 'no choice' but to abandon his plan to hand over the Chagos Islands in the face of an 'openly hostile' Donald Trump, the former Head of the Diplomatic Service said today.

Lord Simon McDonald, who was in charge at the Foreign and Commonwealth Office when the UK was advised to hand back the Indian Ocean island archipelago to Mauritius, said the plans would now go 'into the deep freeze'.

And the former senior diplomat warned it could take decades to work out a plan for the islands, currently under British sovereignty and officially named the British Indian Ocean Territory, calling the issue 'a hangover from the end of the Colonial era'.

His comments came as UK government officials said Starmer's plan to hand back the islands and lease back the land where the strategic UK-US military base of Diego Garcia is sited had not been 'abandoned altogether'.

But the controversial handover, which was expected to feature in the King's Speech in May, has been delayed indefinitely because there is not enough time to bring forward legislation in this Parliament and the US has withdrawn its backing.

Without US backing, the government's plans are stymied indefinitely. Donald Trump, once supportive of the deal which would see the UK pay up to £101m a year to lease Diego Garcia, changed his mind as relations soured between the two allies over the Middle East.

In January, he called the plan an 'act of total weakness'.

'The government had no other choice,' Lord McDonald, who was in charge at the FCO between 2015 and 2020, told the BBC.

'The UK had two objectives. One was to comply with international law. The second was to reinforce the relationship with the United States but when the President of the United States is openly hostile the government has to rethink so this agreement will go into the deep freeze for the time being.'

Speaking to Radio 4's Today programme, the former senior civil servant said there were 'choices over many decades' to change the way the Chagos Islands were governed but that once the government submitted to the legal process of the International Courts of Justice (ICJ), it 'was bound by the outcome of that process'.

In 2019, the ICJ recommended that Chagos should be handed back to Mauritius, triggering the current chain of events.

'Everything that has happened now and also under the Conservative government as well as the Labour government is a consequence of that ICJ judgment,' he said.

While agreeing there was a 'mood to disregard international law' and the judgment to hand back the islands could theoretically be ignored, he said:

'This mood is being led by the United States and Russia and China have always been ambivalent but the US being equally ambivalent is noticed by everybody.

'The UK has always defined itself as a country that respects and upholds international law and I think the government is correct to keep to that traditional policy.'

Lord McDonald said he expected there would be 'no change' to the islands while the Mauritians 'were in no position to take them over by force or would even try because they are over 1200 nautical miles away with no navy to speak'.

He said: 'I think the status quo will persist.'

And he warned it could even take even longer than 50 years to sort out what would happen.

He explained: 'This was an issue that was a hangover from the end of the Colonial era. For the last 200 plus years, successive powers that administered the Indian Ocean administered it as one unit so, at independence, the rules of decolonisation were that the whole unit should become independent as one new country.

'The Brits - to help the US - carved out the Chagos archipelago to allow the Americans to build this absolutely vital base at Diego Garcia. The Mauritians were never happy about that. The whole process took more than half a century. It is going to take even longer to sort it out there.'

Lord McDonald, who sits in the Lords as a Life Peer and is also Master of Christ's College, Cambridge, said he expected negotiations would now continue 'in a low key way' because 'the President has already changed his mind more than once on this issue so it is possible he will change his mind again.

'If he doesn't then there will be a new president in 2029,' he said.

To enact any Chagos bill, the UK, which has controlled the islands since the early 19th Century, requires a formal exchange of letters from the US as a legal necessity.

Any deal would then see the UK formally cede sovereignty and sign a lease for Diego Garcia to maintain the military base.

A government spokesperson said: 'Diego Garcia is a key strategic military asset for both the UK and the US.

'Ensuring its long-term operational security is and will continue to be our priority - it is the entire reason for the deal.

'We continue to believe the agreement is the best way to protect the long-term future of the base, but we have always said we would only proceed with the deal if it has US support. We are continuing to engage with the US and Mauritius.'