When the confederate Scotch lords had taken Mary Stuart prisoner after her defeat at Carberry Hill, and had resolved to dethrone her, they sent her for safe custody to the castle of Loch Leven, situate on a small island in the middle of the lake of that name. They chose this gloomy place, not only because it was nearly inaccessible, but because the hapless lady would there be in the keeping of that most watchful of all gaolers, a mortal enemy. Margaret Erskine, mother of William Douglas, the owner of the castle, had had a son by James V., whom it pleased her to regard as the legitimate heir to the throne of Scotland, and she hated Mary as an obstacle to her schemes of ambition. Religious differences intensified this feeling, for Margaret was a zealous Presbyterian. In short, her character, her faith, her family pride, and the natural harshness of her temper, all conspired to make her an inexorable guardian of the unfortunate Queen.
After Mary had been compelled by violence to renounce the crown in favour of her son, she was placed in the most rigorous confinement, the strictest watch being kept over her to prevent her, not only from effecting her escape, but from holding any sort of communication with the outer world. Many of the sovereigns of Europe were well disposed towards her, but she was not allowed to write to her friends, though she sometimes found an opportunity of doing so while the daughters of Margaret, who shared her chamber, were asleep, or at their meals. The cruelty of these restraints defeated their end, for it touched the very son her gaoler, George Douglas, with compassion for the captive Queen, and led him to form a plan for her escape. But his first attempt to aid her was unsuccessful. It was arranged that the Queen should leave the castle in the dress of the laundress who brought her linen to Loch Leven, and that George Douglas and a number of his partisans should be ready to receive her as soon she had crossed the lake. The appointed day came; the young man was at his post, and the Queen, thanks to her disguise, had actually got clear of the castle, and reached the boat, when one of the boatmen, struck by the figure of the pretended laundress, attempted to lift her veil, and the hasty gesture with which the Queen resisted his touch, revealed a hand too white and too delicately formed to be that of a hard-working girl. The man at once guessed her real rank, but even at that moment Mary did not lose her presence of mind. She declared her name and title, and ordered him, on pain of death, to row her across the lake. The name of Margaret Erskine had, however, greater terror for the fellow than that of Mary Stuart; and the Queen was taken back to captivity again.