The Secret Intelligence Service (SIS), commonly known as MI6 (Military Intelligence, Section 6), is the British intelligence agency which supplies the British Government with foreign intelligence. It operates under the formal direction of the Joint Intelligence Committee (JIC) alongside the internal Security Service (MI5), the Government Communications Headquarters (GCHQ) and Defence Intelligence (DI).
It is frequently referred to by the name MI6 (Military Intelligence, Section 6), a name used as a flag of convenience during the First World War when it was known by many names. The existence of the SIS was not officially acknowledged until 1994.
In late 2010, the head of the SIS delivered what he said was the first public address by a serving chief of the agency in its then 101-year history. The remarks of Sir John Sawers primarily focused on the relationship between the need for secrecy and the goal of maintaining security within Britain. His remarks acknowledged the tensions caused by secrecy in an era of leaks and pressure for ever-greater disclosure. Since 1995, the SIS headquarters have been at Vauxhall Cross on the South Bank of the River Thames.