Few people were aware of SOE's existence. Those who were part of it or liaised with it sometimes referred to as the "Baker Street Irregulars", after the location of its London headquarters. It was also known as "Churchill's Secret Army" or the "Ministry of Ungentlemanly Warfare". Its various branches, and sometimes the organisation as a whole, were concealed for security purposes behind names such as the "Joint Technical Board" or the "Inter-Service Research Bureau", or fictitious branches of the Air Ministry, Admiralty or War Office.