Monteagle was the surname of the peer warned by the 1605 letter that exposed the Gunpowder Plot.
William Parker, 4th Baron Monteagle, received an anonymous letter advising him not to attend the opening of Parliament on 5 November 1605. The warning referred cryptically to a blow that would strike Parliament and urged him to withdraw to the countryside.
Monteagle brought the letter to Robert Cecil, the king’s principal minister. Officials investigated the warning and searched the undercroft beneath the House of Lords. They found Guy Fawkes with the stored gunpowder during the early hours of 5 November, just before the planned attack.
The author of the letter has never been established with complete certainty. Historians have proposed several possibilities, including Francis Tresham, a relative of Monteagle and one of the conspirators, but the evidence remains disputed. The safe answer is the recipient’s title and surname: Lord Monteagle.