By 17 September 1514 those that had supported Margaret, the Bishops of Glasgow, Aberdeen and Galloway and the earls of Arran, Huntly and Home were considering whether she had the right to the tutrix of the young King. . . . The reason for the volte-face by her nobles was because she and Angus had been married in a secret ceremony in August 1514. Perry expresses the canonical view that ‘in one moment of womanly weakness and romantic folly, Margaret Tudor had effectively destroyed her own powerbase.’
While this move brought Scotland to the brink of civil war, her reasons may have been more hard-headed. She and her children were vulnerable in a country largely controlled by a fractious and factious nobility that had no love of her brother Henry VIII, her countrymen and no great affection for her. A marriage with one of Scotland’s greatest nobles was potentially a means of helping her to protect her sons. To marry outside of the realm would have meant leaving her two infant sons behind. It is likely that she knew of her mother’s brothers, Edward V and Richard, Duke of York, the princes in the tower, who disappeared in the hands of their uncle the future Richard III. This would have weighed heavily on her mind.
. . . From a queenship perspective, Margaret had, up to the point where she had remarried without consent of her council, acted as a noble and competent widow, mother and Regent. James IV had been secure enough in her abilities to trust her with the role in his will. Margaret had already demonstrated before his death that she was an able and trusted peacemaker having supported Scotland’s needs before those of her father or brother. She followed this practice as Regent. She had an excellent understanding of the domestic, religious and international affairs of Scotland, and had for the first year as Regent, managed with some success to secure the allegiance of the majority of the nobles. Her marriage to Angus was, however, a mistake.
Lorna G. Barrow, 'Queenship and the Challenge of a Widowed Queen: Margaret Tudor Regent of Scotland 1513–1514', Journal of the Sydney Society for Scottish History, 16