I saw on the BBC News website a piece about the history of music recorded by the singers Alamire which has reached no 2 in the classical charts. The music was composed or compiled by the Bavarian-born Petrus Alamire and presented in a prestigious choir book to King Henry VIII in 1516. The manuscript is now in the British Library.
Alamire was more than just a talented court musician - he was also a spy, using his privileged position to glean information. Apparently recruited to do this on behalf of the King by infiltrating the household of the exiled Yorkist claimant Richard de la Pole -King Richard IV in his own eyes- and reporting back to London. This Alamire did, but then apparently turned into a double agent for Pole.
Richard de la Pole was killed fighting with the French forces at the battle of Pavia in 1525, and his claim died with him.
The article can be read at Henry VIII, the choir book and Alamire the spy
Thinking about it I suppose it puts the activities of Anthony Blunt in a historical context - it is not so new after all to have double agents working in the Royal household.