Andy Burnham, who is widely expected to succeed Sir Keir Starmer as prime minister on 20 July, has confirmed he will keep Jonathan Powell as national security adviser, prompting fresh concerns that he intends to revive Labour's contested agreement to cede sovereignty of the Chagos Islands to Mauritius. Powell led the Government's negotiations on the deal, so his retention is being read as a signal that Burnham may attempt to push the arrangement through once in Downing Street.

Under the proposed deal, Britain would hand the Indian Ocean archipelago to Mauritius and then lease back the UK-US military base on Diego Garcia for 99 years, paying an average of £101 million a year — around £3.4 billion in total by the Government's figures, though critics claim the true cost could reach £35 billion. Opponents also warn about ceding control to Mauritius, which is regarded as an ally of China. Parliamentary ratification stalled earlier this year after US President Donald Trump withdrew his support, which many had assumed would end the plan.