Recently declassified Intelligence archives from a government report written in 1922 and classified for 90 years, reveal that just before, and during, World War I, London became the focus of a large German espionage offensive. The authors were among the first to obtain access to these newly available documents.
Two organisations, one collecting military information for the Kaiser, the other reporting to the Admiralstab (the German Imperial Admiralty Staff), were dedicated to the creation and management of networks of spies infiltrated into Great Britain from neutral territory, usually the United States and the Netherlands. Dozens of agents, under a variety of ingenious and plausible covers, ranging from cigar salesmen to circus and music-hall performers, traveled to London.
Responsibility for the detection of these, and many other, enemy spies, was left to the country’s principal counter-espionage agency, MI5, which was based at several offices in the West End, and led by a remarkable army officer, Vernon Kell who, despite chronic asthma and poor health single-handedly created an organization that is the forerunner of today’s Security Service, the headquarters of which are such a landmark on the Thames Embankment, overlooking Lambeth Bridge.