An alternative, independent intelligence-gathering network run by the Secret Intelligence Service prior to World War II in parallel to, but in isolation from, the conventional Passport Control Offices. Z personnel usually operated under commercial or journalistic cover across Europe. They were directed from offices in Bush House, on the Strand, and were attached to such businesses as Geoffrey Duveen & Co., Alexander Korda’s London Films, and a travel company. In addition, Z’s chief, Claude Dansey, succeeded in recruiting many of his personal contacts, among them some well-known foreign correspondents such as Geoffrey Cox, Frederick Voight, and Eric Gedye.
In September 1939, Z personnel were instructed to make themselves known to the local passport control officer (PCO), wherever they were, and to continue their intelligence-gathering activities in tandem. In reality many PCOs were skeptical about the quality of Z personnel and the reliability of their networks. When Capt. Sigismund Best was abducted at Venlo in November 1939, it was assumed that whatever advantage had been achieved by the Z Organisation had been compromised permanently.