Indian separatists plotted to kill Sir Winston Churchill during his near disastrous lecture tour of the United States, newly uncovered papers reveal.

FBI agents were drafted in to protect him from the shadowy Ghadr organisation for his 1931 trip across the Atlantic, files at the National Archives at Kew disclose. 

Police feared a fugitive hitman would target him – and so the future wartime leader had his Special Branch bodyguard Sgt Walter Thompson with him and he personally paid the officer's food and lodgings for the trip.

It had been known that Churchill received death threats from Indian groups because of his trenchant support for the British empire. Historians dismissed them as nebulous but the files show Churchill was warned of a plot by California-based terrorists who were part-funded by Moscow.

Pictured: Former prime minister Winston Churchill, then a backbench MP, is wheeled out of a hospital in New York after being knocked down by a car after arriving in the US. The future wartime leader was the target of a plot by the Ghadr organisation

A Home Office memo sent to Churchill – then a backbench MP – in November 1931 alerted him. It said: 'The Ghadr Society has its headquarters in California. It is composed mostly of revolutionary Sikhs from the Punjab.

'At a recent meeting of the Society, a list was put forward of four or five persons whom it was thought desirable to remove, and a man who is now wanted for murder in California volunteered to undertake the removal, either of all the four or five persons or of one named individual. 

Lately the proposed assassin has fled from justice. The India Office have a good line of information on this society, and would get information quickly if there was anything moving. There would, however, be special danger in a visit to California.'

Churchill then arranged a meeting with the Home Office and was told the threat specifically named him, according to the files. He had just returned to the Commons but was without a government job.

Churchill showing his victory sign in around 1941. FBI agents were drafted in to protect the politician on his visit across the pond in 1931

Instead, he embarked on a lecture tour of North America, hoping to recoup financial losses from the Wall Street Crash. He wrote, in another newly disclosed memo, at the end of the tour that the threat had been so serious FBI agents were tasked with staking out each venue ahead of his arrival.

Thompson later referred in his memoirs to a 'very correctly dressed Indian' who entered the lecture hall in Chicago. He believed 'his intention was to kill my man and you could see this in his eye'. Thompson wrote that he had drawn his gun, and the man ran into the arms of two plain-clothes officers, although he managed to escape.

Until now, no credible evidence has emerged to support this claim. David Freeman, of the International Churchill Society, said the documents presented 'fresh material' not previously included in the numerous Churchill biographies.

But it was not the threat of Ghadr that nearly did for Churchill during the trip. Days into the visit in New York, when crossing the road, Churchill looked the wrong way.He was knocked down and suffered a 'severe' head wound, but recovered to continue the tour.