Donnchadh's granddaughter Marjorie (Marthoc, Martha, Margaret), who later held the title in her own right, married Robert de Brus, who later became Lord of Annandale. Their son, also named Robert and known as "Robert the Bruce", would later rule Scotland as King Robert I, causing the earldom to merge into the Crown. Robert was also created a baron in the Peerage of England by writ of summons in 1295 as Baron Bruce of Anandale; the title became abeyant with the death of his son David II in 1371. Thereafter, successive Kings of Scots re-created the Earldom several times, but made it non-heritable, specifying that the earldom would revert to the Crown upon the death of the holder. Thus several creations ended with a reversion to the crown or with the holder becoming King.
In 1469, the Scots Parliament passed an Act declaring that the eldest son of the King and heir to the throne would hold the Earldom, along with the Dukedom of Rothesay. After the Union of the Crowns of Scotland and England, the Dukedom and Earldom have been held by the eldest son and heir of the Kings of England and Scotland, later the Kings of Great Britain, and finally the Kings of the United Kingdom. Compare the Duchy of Cornwall.
In 1628 King James VI and I created John Stuart Earl of Carrick, in Orkney, in the Peerage of Scotland. He had already been made Lord Kincleven in 1607, also in the Peerage of Scotland. Stuart was a younger son of Robert Stewart, 1st Earl of Orkney, illegitimate son of King James V of Scotland. Lord Carrick had no legitimate male issue and the titles became extinct on his death in 1652.
