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Queen Elizabeth II responded to the news that one of her most senior courtiers was a Russian spy “very calmly” despite being shielded from the truth for more than a decade, official documents show.
In 1964, Sir Anthony Blunt, the surveyor of the Queen’s pictures and distinguished art historian, finally confessed he had been a Soviet agent since the 1930s.
He was recruited while studying at university, later forming part of the infamous soy circle known as the Cambridge Five.
However, declassified MI5 files released to the National Archives in Kew, west London, show that the late Queen was not informed of the situation until 1973, when the Government feared that the truth was about to be made public for the first time.
As a senior MI5 officer during the Second World War, Blunt provided Soviet intelligence officers with 1,771 documents between 1941 and 1945.
But his true identity was kept under wraps, and he was offered immunity – and able to keep his job at Buckingham Palace – in exchange for a confession and cooperation in ongoing investigations.
Hot on the heels of the Profumo Scandal, his identity was concealed because officials feared a major scandal would unravel if the public found out the truth.
When the monarch was eventually told in February 1973, she gave a characteristically dignified response.
Prime Minister Edward Heath had instructed the Queen’s private secretary, Sir Martin Charteris, to inform the monarch over concerns that journalists were about to break the story.
On March 19, MI5 director general Michael Hanley reported that the cabinet secretary Sir Burke Trend had shown him a “personal manuscript letter” from Sir Martin confirming she had finally been told.
“Charteris wrote that he had spoken to the Queen about the Blunt case. She took it all very calmly and without surprise,” Mr Hanley noted.
Professor Christopher Andrew explains her composed response in the official history of MI5, suggesting that the monarch was not entirely in the dark about Blunt’s treachery.
The academic notes that Mr Heath was later informed the Queen had been told “in more general terms about a decade earlier”.
However, she apparently made no mention of any earlier briefing, simply acknowledging she had been aware of suspicions about Blunt when his fellow spies, Guy Burgess and Donald Maclean, fled to Russia in 1951.
“Obviously somebody mentioned something to her in the early 1950s, perhaps quite soon after her accession,” Mr Hanley wrote.
Four months earlier, in November 1972, Mr Hanley had met Sir Martin to urge the Palace to sever its links with Blunt.
Sir Martin, however, refused, saying there was little point as Blunt’s position was anyway drawing to a close.
“Charteris thought the Queen did not know and he saw no advantage in telling her about it now; it would only add to her worries and there was nothing that could done about him,” Mr Hanley reported.
“Contrary to what Blunt may have said in the past, Charteris affirmed that the Queen was not at all keen on Blunt and saw him rarely.”
The files suggest that, up until that point, contacts between MI5 and the Palace over Blunt had been sporadic.
In April 1964, the then director general, Sir Roger Hollis, briefed Sir Martin’s predecessor, Sir Michael Adeane, just as they were about to confront Blunt with the new evidence of his treachery which finally led him to confess.
Sir Michael was apparently not briefed again until October 1967, more than three years after Blunt finally owned up, and then only because there was a “risk of publicity” due to a Sunday Times investigation into another of the Cambridge spies, Kim Philby.
Remarkably, the Queen’s ignorance of what was going on was matched by that of her then prime minister, Sir Alec Douglas-Home, who also was not informed of Blunt’s admission.
In an extraordinary misjudgment for which he later apologised, home secretary Henry Brooke, who was in the know, chose not to tell him because he did not want to “add to his burdens”.
Overall, the files suggest MI5 was deeply reluctant to share information about the case with anyone in government – as late as July 1965 Sir Burke had still not been informed, nor had any ministers in the new Labour government which had taken office the previous October.
Blunt was finally unmasked by prime minister Margaret Thatcher in a Commons statement in 1979. He died in 1983 aged 75 having been stripped of his knighthood.
The files are being released now ahead of the opening in the spring of a major new exhibition focusing on the work of MI5 being staged at the National Archives.