Despite his confession, palace officials chose not to inform the Queen, allowing Blunt to retain his job, knighthood, and social standing.

Anthony Blunt, a cousin of Queen Elizabeth II and a member of the royal household, was revealed to be a double agent for Moscow, as disclosed in recently released MI5 archives.

The Queen was finally informed of Blunt's spying activities in 1973 when he was ill, and she reportedly received the news calmly, having known of his past suspicions since the early 1950s.

The release of documents detailing Blunt's activities coincides with an upcoming exhibition titled 'MI5: Official Secrets' at the National Archives in London, which aims to increase transparency about Britain's intelligence services.

During this confrontation, Blunt confessed to his espionage activities, admitting to contact with Russian intelligence after the war and revealing he had declined an invitation to flee with fellow spies Burgess and Maclean.

Few outside MI5 were informed about the seriousness of Blunt's confession, with only the Home Secretary and top civil servants being briefed, while the Queen's private secretary was merely told that Blunt was implicated.

Following his confession, Blunt reportedly felt 'deep relief' and was allowed to keep his position near the Queen, with the approval of four successive British Prime Ministers.

Blunt had previously worked for MI5 during World War II and had been interviewed multiple times, consistently denying any espionage until confronted by MI5 interrogator Arthur Martin in April 1964.

Blunt's espionage was publicly revealed by Prime Minister Margaret Thatcher in 1979, leading to him being stripped of his knighthood, although he was never prosecuted and passed away in 1983.

The exploits of the Cambridge spies, including Blunt, have inspired various cultural works, such as the 2023 series 'A Spy Among Friends' and a portrayal in the 2019 episode of 'The Crown'.

Biographer Miranda Carter suggested that Queen Elizabeth II may have been informally informed of Blunt's espionage activities after 1965, as officials sought to maintain plausible deniability regarding her knowledge.

Despite longstanding suspicions about his loyalty, Blunt was allowed to keep his position due to fears that his dismissal would lead to a major scandal.