and people build careers on their ability to exploit that uncertainty.

So it is fitting, amid the revelations about traitors Kim Philby and Anthony Blunt, that we should find the most sphinx-like figure of all, the late Queen herself.

The National Archives in Kew have released papers which purportedly spill the beans on one of the big unknowns of British public life from the Cold War era:

when did Queen Elizabeth II learn that the ultra-respectable Keeper of the Queen’s Pictures, and one of the country’s most distinguished art historians, Sir Anthony Blunt, was a spy for the Soviet Union, having signed up with Moscow in the 1930s? Suspicion mounted around Blunt during the 1950s, and in 1964, after undeniable evidence emerged, he confessed in exchange for immunity from prosecution.

Blunt’s guilt did not become public knowledge until 1979, when he was stripped of his knighthood. He lived the remaining three years of his life scared to go out for fear of public opprobrium. We knew that the prime minister at the time of Blunt’s confession – Sir Alec Douglas-Home – was not told, but, curiously, home secretary Henry Brooke was (and apparently he didn’t want to bother his boss with it). But at what point in those intervening 15 years was the monarch informed?

The conundrum as to whether to tell Her Majesty has long fascinated Whitehall-watchers. As a matter of security, was it necessary for the Head of State to be told of this potential embarrassment – or worse – at the Palace, or should she be protected from – and remain uncontaminated by – a story that had supposedly run its course? After all, Blunt had confessed, no action was to be taken against him and he was deemed unable to do any further harm.

On the other hand, the political picture was a shambles. Harold Macmillan’s Conservative government had suffered a series of body blows, the latest of which, the Profumo affair, had revealed that the secretary of state for war had lied about having an extra-marital relationship with a 19-year-old who was also seeing a Soviet naval attaché. With Labour parading its anger at cover-ups in high places, a further embarrassment might have brought down the government. With the collapse of Macmillan’s government in 1963, further revelations about spies in the upper echelons of British society may well have destabilised Douglas-Home’s administration.

Yet if keeping a lid on Blunt’s guilt could be maintained in exchange for telling all he knew (which he almost certainly didn’t), where was the harm?

The thorniness of this dilemma, and the extent of the Queen’s knowledge, were the subject of one of Alan Bennett’s finest plays, A Question of Attribution. In the play, the Queen toys with the uncomfortable Blunt, talking airily in a conversation supposedly about paintings about “fakes”, suggesting that she was indeed aware of his treachery without, of course, spelling it out. The scene had a remarkable ring of truth, though it was based for the most part – though not entirely – on speculation by Bennett. Its brilliance survives yesterday’s release intact.

Now we have been let in on the secret, or rather an Official Secret. The Queen was not told formally until 1973, when Blunt appeared to be at death’s door, which would have put him beyond the protection of the libel laws. To prepare for the potential embarrassment – perhaps the most potent spur among the Establishment – of a media storm following Blunt’s death, Sir Martin Charteris, the Queen’s private secretary, informed her. Did the Queen punch the air and shout, “I knew it. I always thought he was a wrong’un!” Again, the details are scant. We are told no more than that “she took it all very calmly and without surprise.”

Well, she would, wouldn’t she? Because, as has been reported, the truth is that she had been informed of his treachery about ten years earlier. And what was official historian Professor Christopher Andrew’s source for writing this; “Security Service Archives.” So may we see those too, please?

Apparently not. There is seemingly little likelihood of the relevant papers seeing the light of day for years, so we are left relying on MI5’s Peter Wright, who wrote in Spycatcher that Michael Adeane, the Queen’s private secretary in 1964, had told him he wanted to know only as much as he needed to know. Adeane confirmed that the Queen was fully informed and she was “quite content for him to be dealt with in any way that gets to the truth.”

Given that in the early 1960s a still deferential media knew nothing of Blunt’s confession and was unlikely to embarrass the monarch with any difficult questions, let alone hot-potato ones like this, it seems likely that “a quiet word” – and an officially deniable one, though one still noted in the spooks’ archive – about Sir Anthony’s sympathies in an earlier life would have been the safe way forward.

In other words, what we have been told this week is the official version. It was, and remains, a heroically British fudge. The Queen’s personal relations with Blunt are not well documented. She is said to have found him remote, but also to have been amused by him. But certainly he was very much part of the Palace scene, not just a hired accumulator of works of art. The Queen Mother was a third cousin of his, and he had been trusted sufficiently to be sent to Germany at the end of the war on a secret mission to rescue some valuable and possibly incriminating items. Historian Jonathan Haslam has revealed that Blunt felt sufficient loyalty towards the royals that he told his Soviet masters he would do nothing to break their confidence in him.

Though his demeanour could be lofty and cold, Blunt was also well regarded in the household. The most striking example of this was the letter he received from the King in 1979 after his public exposure. As a human gesture, the then prince wrote a supportive, sympathetic and regretful message to Blunt. “Anthony was on the verge of tears as he read the letter,” remembered his friend Brian Sewell. “He had a catch in his voice.” A year or two later, Blunt was seen at the opera with the Queen Mother, another gesture of support and sympathy.

But the Queen, eyes ever on the job, had to retain her professional, vocational distance and public inscrutability throughout. In this she was abetted by her civil servants, immaculately schooled in the art of diffusing, distracting and providing their bosses with plausible deniability. She remained above the grubby fray, and, it could be safely assumed, only the insolent and ill-mannered would have wanted to draw her into it.

Which brings us to where we are today. We continue to know very little about what exactly she knew, how she reacted, what if anything she confided to those around her. On the broader espionage question, we continue to speculate – because we can do no other – and play the game of being slowly drip-fed papers containing buried nuggets, filling in bits of the jigsaw until the next drop from Kew.

For now, though, we are left poring over this recent, and rather enormous, batch, trying to see if the established narratives require revision. The new papers from Kew tell us little about what was known of Blunt’s activities for the Russians in the 1940s and 1950s but a lot to show that his 1964 confession was no surprise to insiders. After his friend Guy Burgess had defected in 1951 – to the huge embarrassment of both Blunt and Kim Philby, on whom suspicion now centred, he continued to offer incriminatingly vague answers when interviewed.

By the end of the decade he had been all but rumbled, had a de facto immunity – because of his links to the Palace and the lack of a smoking gun – and was purportedly ostensibly helping out with the clean-up of the intelligence community. Also unmentioned in the new papers is the fact that at very short notice Blunt visited his old friend Philby in Beirut in late 1962 – a year after Philby apparently tried to re-recruit the disenchanted Blunt – seemingly to warn Philby of his imminent exposure. Or was he on some other sort of mission? The fact that we have not been reassured on these issues adds to a continuing public fascination with a secret world that by rights we should have left behind long ago.

The new papers on Philby fill in some gaps, continuing to show the best and worst of the intelligence community. The interview conducted by MI6’s Nicholas Elliott with his old friend and tormentor Kim Philby in Beirut remains mysterious. Shortly afterwards, Philby vanished, turning up later in Moscow, having defected and leaving his wife to field the question of a sceptical media. (How could she not have known, they asked).

A few months ago the person who transcribed the interview died, which may have been the cue for the release of the exchanges, but they still fail to answer the question of whether Elliott was giving Philby a green light to make a run for it, or whether Elliott, not for the first time, was outwitted by the friend he had defended so stoutly from the charge of treason. Somewhere there must be a document that answers that question. Until it appears, we’ll have to go on playing the game.