Margaret Stewart of Ochiltree was the daughter of Andrew Stewart, 2nd Lord Ochiltree, and Agnes Cunningham. In March 1564, at the age of 17, she married the 51 year old John Knox, one of the leading figures in the Presbyterian Reformation of Scotland. John Knox's first wife, Marjorie Bowes, daughter of Richard Bowes, the constable of Norham Castle, had died in 1560.
What might today seem a very odd match on the grounds of Margaret's youth and the age difference between her and Knox did not seem so unusual at the time. Margaret's family was strongly Protestant, and it seems that in their eyes, and hers, she was marrying the hero of the age, the man who had rid Scotland of Catholicism. The fact that Margaret's family was part of Scotland's aristocracy, distantly related to the Stuart monarchs, and John Knox certainly wasn't, did apparently cause Mary Queen of Scots to pass unfavourable comment: but John Knox had never gone out of his way to endear himself to Mary anyway.
Margaret lived with Knox in what is now known as John Knox's House on Edinburgh's Royal Mile, and they had three daughters together. She also became his secretary, and, at the end of his life, his nurse. John Knox died in November 1572. In early 1574, still only 27 years old, Margaret married again, this time to Sir Andrew Ker of Faldonside. She moved to his home at Faldonside House on the banks of the River Tweed south of Galashiels, and they had a number of children together. Margaret Stewart died in 1612.