On 7 June 1690, three weeks before the Battle of the Boyne (which was fought on 1 July in the Old Style calendar), John Skeffington, 2nd Viscount Massereene, wrote to Ireland from London to report the latest intelligence received concerning the activities of James II, his supporters and the war effort; this information was to be passed on to King William. Sandwiched between news about battle preparations and warnings about possible attempts on William's life, he related the following:

The woman named by Lord Massereene was Sarah Stafford, wife of Francis Stafford of Clonwen. As a direct descendant of Hugh O’Neill, earl of Tyrone, she was connected to one of Ireland's most famous families. She was also, as this letter shows, running a ring of pro-Jacobite informants in the midst of one of the most politically tumultuous periods of Irish history. Nor was she alone, being only one among many women doing the same thing. To be in contact with James and spoken of to William, they must have been serious political players, and Massereene's description of Sarah's activities shows why. She was well organised, well enough financed to hire employees to do her bidding and in control of a news network which was growing by the day and feeding her apparently accurate information on the forces and troop movements of the Williamite general, Friedrich Schomberg, duke of Schomberg. She, and other ladies like her, posed a real threat to the Williamite cause and, despite the fact that her natal family were also highly political (Massereene also reported that ‘one MacDonnell [perhaps a brother of Sarah’s?] without all doubt is sent from the late King James to the highlands of Scotland to stir up new trouble in those parts’), there is no hint that she was being used as an unwilling pawn.