This view has been challenged by Nicholas Hiley who has asserted that it is a complete fabrication.
In 2006 his article "Entering the Lists" was published in the journal Intelligence and National Security outlining the products of his research into recently opened files.
The service has had a national headquarters at Thames House on Millbank in London since 1995, drawing together personnel from a number of locations into a single HQ facility.
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It liaises with SIS, GCHQ, DIS, and a number of other bodies within the British government and industrial base.
It is overseen by the Intelligence and Security Committee of Members of Parliament, who are directly appointed by the Prime Minister, by the Interception of Communications Commissioner, and by the Intelligence Services Commissioner.
Information held by the service is exempt from disclosure under section 23 of the Freedom of Information Act 2000.
The Security Service is derived from the Secret Service Bureau, founded in 1909 and concentrating originally on the activities of the Imperial German government as a joint initiative of the Admiralty and the War Office.