British secret intelligence did not tell Queen Elizabeth II that her royal art adviser confessed to spying for the Soviet Union for almost a decade, according to newly released documents. The revelations come from a large tranche of documents made public by British intelligence service MI5 on Tuesday.

The files about royal art historian Anthony Blunt are among a trove from the intelligence agency MI5 released Tuesday by Britain’s National Archives.

Queen Elizabeth II was not told officially for nearly a decade that one of her most senior courtiers had admitted he was a Soviet spy, newly declassified British files revealed Tuesday.