Proper noun
MI5
The domestic intelligence and counter-espionage agency of the United Kingdom, which operates in secret and whose primary function is to spy on terrorist organizations and others viewed as a threat to British national security. Formally known as the Security Service.
A Government spokesman responded to the MI5 allegation by saying: “The Home Secretary and MI5 have a strong and close working relationship, and baseless claims to the contrary are both wrong and against the public interest. Source: Internet
After the war Chapman and his Rolls-Royce On his retirement, MI5 expressed some apprehension that Chapman might take up crime again when his money ran out and if caught would plead for leniency because of his highly secret wartime service. Source: Internet
Attlee agreed with MI5 that he faced, "a very present menace." Source: Internet
B1A (the Counter-Intelligence Division of MI5 ) had done a good job intercepting all of the German agents in Britain. Source: Internet
Eventually transmissions purporting to be from one double agent were facilitated by transferring the operation of the set to the main headquarters of MI5. Source: Internet
Bennett had free and unfettered access to the archives of the Foreign Office, as well as those of the Secret Intelligence Service (SIS) and MI5. Source: Internet