Walsingham had a network of spies in every town. Some of his agents were paid and trained by the government, while others were paid informants
Paid informants were people who knew the plotters against the queen and could help investigate. An example was John Hart, who agreed to help the investigation if he was pardoned
Walsingham also had spies abroad, such as France, Spain and North Africa
Walsingham used ciphers which would be written in code and then decoded when the letter was received to communicate
Walsingham tortured Priests to encourage Priests to give information. Walsingham executed around 130 priests and 60 of their supporters
Walsingham only used torture in serious cases, as he did not want to make martyrs of plotters