A separate booklet is available from HMSO describing the work of the Security Service in more detail. The Secret Intelligence Service, sometimes known as MI6, similarly originated in 1909 as the Foreign Section of the Secret Service Bureau, under RNR Commander, later Captain, Sir Mansfield Cumming, which was responsible for gathering intelligence overseas. The Act defines the functions of the Service and the responsibilities of its Chief, as well as establishing control and oversight arrangements. The Service's principal role is the production of secret intelligence in support of Her Majesty's Government's security, defence, foreign and economic policies within the framework of requirements laid upon it by the JIC and approved by Ministers. It meets these JIC requirements for intelligence gathering and other tasks through a variety of sources, human and technical, and by liaison with a wide range of foreign intelligence and security services.
Specific operations are subject to longstanding procedures for official and ministerial clearance.
The present Chief of the SIS, who took up his appointment in September 1994, is Sir David Spedding. SIS is based at Vauxhall Cross in London. All enquiries, including employment opportunities, should be addressed to PO Box 1300, London SE1 1BD iii. In 1953 GCHQ moved to two sites on the outskirts of Cheltenham, where it continues to be based. GCHQ derives signal intelligence by monitoring a variety of communications and other signals, such as radars.