In this task he was assisted by John Cunningham of Drumquhassle, Matthew Douglas of Mains (both also retainers of the Earl of Lennox) and a traitor from the castle garrison called Robertson. He was once warden of the castle, knew the topography of the rock well and in particular, knew how it could be scaled. It seems that while in the service of the Governor, his wife was accused of theft and publicly flogged. This episode appears to have provoked Robertson to leave Queen's supporters in the castle and offer his services to the King's supporters, initially to Robert Douglas, who introduced him to Drumquassle.