Neither the official version nor any State paper mentions the place where the letter was delivered, which in such a mysterious matter would be the first inquiry. "Own lodging" at that time signified a person's house. Hoxton is generally stated to have been the place of delivery,[4] which was then a single street in the outlying suburb on the great north road; at a house which Monteagle is known[5] to have occupied, belonging to his brother-in-law, Francis Tresham; and this ownership may have been Salisbury's reason for not naming it, which so curious an omission seems to imply. The letter is as follows:

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. 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, offering him the use of his own purse if he would even defer it.[8] Tresham could indeed have desired nothing less than to become involved in such a matter. His father had recently died, and he had succeeded to a considerable property,[9] which alone induced his first cousin Catesby to bring him into the plot. As Tresham wrote when in the Tower:[10] "I thank God I am owner of such a fortune as is able to afford me what I desire, the comfort whereof is so much the sweeter unto me, as I have spent most of my time overburthened with debts and wants, and had resolved within myself to spend my days quietly."[11] He acknowledged that his intentions with regard to the other conspirators were "to ship them away that they might have no means left them to contrive any more ... then to have taken a course to have given the State advertisement by some unknown means."[11] He was consequently the only conspirator who remained behind and at large after Fawkes was taken and the others had fled. There can be no reasonable doubt that Tresham, though not the writer, was the sender of the letter; and upon this hypothesis all investigators must go, as there is none other at all likely.