German Spies in England by William Le Queux

Some of the cases of espionage within my own knowledge -- and into many of them I have myself made discreet inquiry -- may not prove uninteresting. Foreign governesses, usually a hard-worked and poorly-paid class, are often in a position to furnish important information, and very serious cases have recently been proved against them. These young women have lived in the intimacy of the homes of men of every grade, Cabinet Ministers, Members of Parliament, financiers, officers of both Services, and officials of every class. By the very nature of their duties, and their extreme intimacy with their employers, they are, naturally, in a position to gather much valuable information, and often even to get sight of their employers' correspondence, which can easily be noted and handed over to the proper quarter for transmission to Berlin.

Here is a case already reported by me. Not very long ago, in the service of a very well-known Member of Parliament living in Essex, lived a clever, good-looking, and intensely musical young German governess, who was regarded by the Member's wife as "a perfect treasure," and who took the greatest interest in her two little charges. For over two years Fräulein had been in the service of this pleasant household, being, of course, regarded as "one of the family."