> If you want to find out more about the team’s work on the application of network analysis to the State Papers, see their articles Metadata, Surveillance, and the Tudor State, and A Tale of Two Snowdens: Dataveillance in History
Thomas Cromwell was the most prominent spymaster of Tudor times and letters to him feature heavily here. So not all of it is bulk surveillance, some of it seems to be old-fashioned human intelligence gathering.
That's the point apparently.