Banker and conspirator Roberto di Ridolfi was born in Florence on 18 November 1531 into an aristocratic dynasty. His family operated one of the largest banking houses in Florence. Ridolfi had close mercantile connections with London, settling there about 1562. His employment as a financial agent on behalf of William Cecil gave him a position of influence at the court. By the late 1560s his commercial interests had been eclipsed by politics. He became obsessed with returning England to the Catholic fold. From 1566, he began acting as a secret envoy for the Vatican. He helped smuggle into England and disseminate some eighty copies of Regnans in excelsis, the 1570 papal bull excommunicating Elizabeth I.
He also masterminded the so-called ‘Ridolfi plot’ in 1571. He cultivated a relationship with Thomas Howard, Duke of Norfolk, and persuaded him to sign a declaration stating that he was a Catholic and willing to lead a revolt against Elizabeth. Ridolfi drew up a list of forty peers whom he believed would support the attempt of freeing Mary Tudor and, with the support of Spanish forces, bring her to London where she would supplant Elizabeth. Mary would then secure her throne by marrying Norfolk. Ridolfi travelled to the Continent in March 1571 trying to find support for his scheme, but was met with indifference. It was an ill-conceived plan destined to fail. Ridolfi was unable to return and the English government confiscated his goods. He moved back to Florence where he died in February 1612.