Margrat NcWilliam, a 56-year-old resident of Corsmoire in Rothesay, Bute, first entered the scrutiny of local judicial authorities in 1649, though the formal records of her case culminated in the early 1660s. By the time of her documented trials in 1662, Margrat admitted to a long-standing association with witchcraft, claiming that her involvement had begun as far back as 1631. Her case was deeply entwined with her family; her daughter, Katharin Moore, and her grandson were also accused, marking the proceedings as a multi-generational matter of interest to the local courts. The severity of the investigation is evidenced by the series of recorded confessions extracted from her throughout the spring of 1662, beginning in February and concluding in May.
The reach of the accusations against Margrat extended far beyond her own household, as she was denounced by an extensive network of fourteen other individuals, including John Gely, Elspeth Gray, and various members of the NcNeill and McKaw families. The formal charges brought against her focused heavily on the disruption of domestic economy, specifically citing allegations of property damage directed toward dairy production and local crops. These testimonies, combined with her own repeated confessions, frame the narrative of a woman whose life and reputation were inextricably bound to the social anxieties and legal machinery of seventeenth-century Bute.