The Ridolfi plot was a plot in 1571 to assassinate Queen Elizabeth I of England and replace her with Mary, Queen of Scots. The plot was hatched and planned by Roberto di Ridolfi, an international banker who was able to travel between Brussels, Rome and Madrid to gather support without attracting too much suspicion.
The Duke of Norfolk, a cousin to Queen Elizabeth and the wealthiest landowner in the country, had been proposed as a possible husband for Mary since her imprisonment in 1568. This suited Norfolk, who had ambitions and felt Elizabeth persistently undervalued him. In pursuit of his goals, he agreed to support the Northern Rebellion, though he quickly lost his nerve. Norfolk was imprisoned in the Tower of London for nine months and only freed under house arrest when he confessed all and begged for mercy. Pope Pius V issued Regnans in Excelsis, a papal bull excommunicating Elizabeth, shortly afterward, which commanded all faithful Catholics to do all they could to depose her. The majority of English Catholics ignored the bull. In response, Elizabeth became much harsher to Catholics and their sympathisers.
Roberto Ridolfi, a Florentine banker and ardent Catholic, had been involved in the planning of the Northern rebellion, and had been plotting to overthrow Elizabeth as early as 1569. With the failure of the rebellion, he concluded that foreign intervention was needed to restore Catholicism and bring Mary to the English throne, and began to contact potential conspirators. Mary's advisor, John Lesley, the Bishop of Ross, gave his assent to the plot as the way to free Mary. The plan was to have the Duke of Alba invade from the Netherlands with 10,000 men, foment a rebellion of the northern English nobility, murder Elizabeth, and marry Mary to Thomas Howard, 4th Duke of Norfolk. Ridolfi optimistically estimated half of all English peers were Catholic, and could muster in excess of 39,000 men. Norfolk gave verbal assurances to Ridolfi that he was Catholic, though as a pupil of John Foxe, he remained a Protestant all his life. Both Mary and Norfolk, desperate to remedy their respective situations, agreed to the plot. With their blessing, Ridolfi set off to the Continent to gain Alba, Pius V and King Philip II's support.
In 1571, Elizabeth's intelligence network was sending her information about a plot against her life. By gaining the confidence of Spain's ambassador to England, John Hawkins learned the details of the conspiracy and notified the government so to arrest the plotters. She was also sent a private warning by the Grand Duke of Tuscany, who had learned of the plot against her. Charles Baillie, Ridolfi's messenger, was arrested at Dover for carrying compromising letters, and under torture revealed the plot. The Duke of Norfolk was arrested on 7 September 1571 and sent to the Tower. Guerau de Spes, the Spanish ambassador, was expelled from the country in January 1571. Still abroad when the plot was discovered, Ridolfi never returned to England; he became a Florentine senator in 1600.
An altered and fictionalised version of the Ridolfi Plot was featured in the 1998 film Elizabeth, starring Cate Blanchett as Elizabeth. Christopher Eccleston played Thomas Howard, Duke of Norfolk as the chief conspirator and the film omitted the involvement of Ridolfi. In the film the conspiracy included Bishop Stephen Gardiner, a counter-reformer who had died in 1555 before Elizabeth's accession, and John Ballard, who was involved in the later Babington Plot.
- Dures, Alan (1983), English Catholicism, 1558–1642: Continuity and Change (1st ed.), Longman, ISBN 978-0-582-35229-2
- Elton, G. R. (1978), England under the Tudors, University Paperback
- Jenkins, Elizabeth (1958), Elizabeth the Great, Phoenix Press
- Lockyer, Roger (1964), Tudor and Stuart Britain, 1417–1714, Longman
- Morris, T. A. (1998), Routledge Unknown parameter
|\title=ignored (help); Missing or empty
- Smith, A. G. R. (1967), The Government of Elizabethan England, Edward Arnold
- Starkey, David (2001), Elizabeth, Vintage, ISBN 978-0-09-928657-8
- Weir, Alison (2008), Mary, Queen of Scots: And the Murder of Lord Darnley, Vintage, ISBN 978-0-09-952707-7
- Williams, Neville (1972), The Life and Times of Elizabeth I, Book Club Associates