Weis' "Ancestral Roots. . ." (89:27), (170:25). Cockayne's "Complete Peerage" calls her the illegitimate daughter of King William the Lion. She was the widow of Robert de Brus (or Bruce), son of King Robert II of Scotland. Stewart Ross, in his book, "The Monarchs of Scotland", concerning the
subject of the relations between King Alexander II of Scotland and King Henry III of England, writes, "For the rest of the reign relations between the countries centered around two issues. When Henry III felt piqued towards Alexander, as in 1323, he would raise again the issue of England's supposed suzerainty over Scotland. For his part, Alexander would respond by raising the hoary question of Northumbria and drawing Henry's attention to an agreement of 1209, by which Alexander's sisters,
Margaret and Isabel, were sent to England with a massive dowry of 15,000 marks to marry the sons of King John. (The exact wording of the treaty was unclear and the Scots also conveniently forgot that they had never paid the dowry in full.) No marriages had taken place. In the end the problem was settled amicably in 1237. In return for grants of land in northern England and Cambridgeshire, Alexander gave up his claims to Northumbria and forgot about the dowry. Suitable barons were found who were prepared to take Alexander's sisters off his hands."