Buchan was the first Mormaerdom in the High Medieval Kingdom of the Scots to pass into the hands of a non-Scottish family in the male line.

The earldom had three lines in its history, not counting passings from female heirs to sons.

The latter is the only significant source for the mormaerdom, and its existence makes Buchan one of Scotland's best documented provinces for native cultural institutions.

After the death of Fergus, before 1214, Buchan became the first native mormaerdom to pass into the hands of a foreign family, the Comyns, though only through marriage.

Alexander Comyn, Earl of Buchan inherited and continued his mother's title and line until it was conquered and forfeited during the Wars of Scottish Independence.

The title descended in the direct male line until the death of his grandson, John, the third Earl, in 1551.

This line of the family failed on the death of their grandson, the eighth Earl, who died unmarried in 1695.

His eldest surviving son, David, the eleventh Earl, was the founder of the Society of Antiquaries of Scotland but is best remembered as an eccentric.

He was educated at Eton College and was styled as Lord Cardross between 1984 and 11 September 2022, when he succeeded to the peerages.