He is credited with writing propaganda decrying a conspiratorial marriage between Mary and Thomas Howard, 4th Duke of Norfolk, and Roberto di Ridolfi, after whom the plot was named, was interrogated at Walsingham's house.
Han bliver krediteret for at have skrevet propaganda om ægteskabet mellem Maria og Thomas Howard, 4. hertug af Norfolk, og Roberto di Ridolfi, som komplottet blev navngivet efter, blev forhørt i Walsinghams hus.