John Cassell,
Cassell's Illustrated History of England
(1865)
“ Therefore the country swarmed with spies and informers; and Walsingham, as a man of a detective genius, was kept hard at work to trace, by his secret emissaries, every concealed movement of sedition. Both at home and abroad he had a host of agents under a multitude of disguises. The society of Jesuits never had a more expert and fearless general, nor a more varied army of informers. They presented themselves in the shape of travelling noblemen, of physicians, of students in Popish seminaries. They swarmed in seaports lying betwixt England and the different chief Continental routes. ”
