BBC News at the National Archives
Previously unseen documents show Churchill was "surprised" by the leak
Details of a death threat aimed at Sir Winston Churchill's wife have been released by the National Archives.
News of the threat to the then prime minister's wife was leaked to the press, much to Sir Winston's displeasure, according to previously unseen documents.
The letter, addressed to Lady Churchill and dated 15 March 1954, reads: "I, as well as my brave and most ruthless gang, will be out to shoot you dead at any moment in Britain."
The threat appeared to be linked to the Mau Mau rebellion in Kenya, which was at its height at the time.
It continued: "End British atrocities in Kenya now! Then live freely in Britain. I am demanding the withdrawal of all troops from Kenya within two months time."
The letter, which ends "yours most wickedly", was penned by a person who referred to themselves only as "Mau Mau Rep, General Stalin".
Documents uncovered at the National Archives at Kew, London, show that the threat was taken very seriously.
The letter was sent to the home secretary's private secretary, as well as Scotland Yard, with orders to improve security surrounding the prime minister's wife by providing her with a detective.
But, according to the documents, it was with "considerable surprise" that Sir Winston discovered news of the threat had been reported in the first edition of the Evening News - a London newspaper - the following day.
Other newspapers also covered the story throughout the day, inundating Downing Street, the Home Office and Scotland Yard with enquiries.
A second letter arrived at Downing Street following press coverage of the death threat.
Letters were hastily exchanged between Downing Street, the Home Office and Scotland Yard in efforts to establish the source of the leak.
Police investigations were launched to establish who wrote the letter, as well as the source of the leak.
But the inquiries failed to unearth any evidence in either case.
Metropolitan Police Commissioner Sir John Nott-Bower wrote to the Home Office two weeks after the first letter was sent, outlining the outcome of the police force's inquiry.
It read: "It has not been possible to discover the source of the leakage and all we can get from the press in confidence is that the information was received from a 'runner', who, so far as they know, is quite unconnected with the
His letter continues: "The matter has been thoroughly investigated and though it is disappointing that it has led to no positive conclusions, I can see no scope for further enquiries.
"The investigations into the source of the threatening letter itself are
being very actively pursued by the Special Branch."
But in a suggestion that the threat was not taken seriously after initial fears, his letter ends with a brief reference to "one new development ...which seems to indicate that the threat is probably not a serious one".
Precise details of that development were not revealed.
The documents - along with other papers - were released by the National Archives and will be available to the public from 4 January.