Mitrokhin

He then went to the UK embassy where he was put in touch with a young member of the staff who asked him: "Would you like a cup of tea?", before getting in touch with MI6 who later exfiltrated him and his family. 

Some Italian ministers said that the archive "is not a dossier from the KGB but one about the KGB constructed by British counter-espionage agents based on the confession of an ex-agent, if there is one, and 'Mitrokhin' is just a codename for an MI5 operation"