The Identification of the Writer of the Anonymous Letter to Lord Monteagle in 1605

In each instance, Catesby was careful to impose the oath and engage the faith of the conspirator, before disclosing the plot; and Tresham, the thirteenth and last, sworn conspirator, on hearing the particulars,

entirely disapproved of the conspiracy, from which he tried to dissuade Catesby,

It was the opinion of the other conspirators, as well as of the Jesuit priests who became involved in the plot through the confessional, that the warning letter originated with Francis Tresham, whose sister was Lady Monteagle, and another sister had married Lord Stourton; and Tresham had been most earnest with Catesby that those two lords, particularly Monteagle, should be warned.