Shadow Networks: Identifying Intercepted Letters in the Elizabethan State Papers Foreign.

Combining traditional and digital methods, this essay models a new toolbox for analyzing the knotty problem of how many letters in the State Papers were introduced to the archive through interception. Estimates by scholars vary widely. Using the State Papers Foreign metadata for the reign of Elizabeth I, we employ a method of "layered searching" to find letters involving a third party. By structuring the communications as a network, we weight edges between correspondents and the Tudor State to distinguish acts of interception from forwarded letters or spy reports. These methods suggest likely candidates for interception with a sliding scale of confidence, helping to identify two broad models of letter interception outside England, which we dub "military-diplomatic" and "catch-and-release." Overall, we estimate more than 5 percent of the collection to have been intercepted, highlighting a continuous network of intercepting officials from the Dutch Revolt to the imprisonment of Mary Stuart. [ABSTRACT FROM AUTHOR]