The title Earl of Morton was created in the Peerage of Scotland in 1458 for James Douglas of Dalkeith.

The family seat is Dalmahoy Farms, Morton near Kirknewton, West Lothian.

[4] The 4th Lord Dalkeith succeeded to his estates upon the resignation of his father c. 1457 and in 1458 was raised to the peerage as Earl of Morton, prior to his marriage to Joanna, the mute deaf daughter of King James I.

When in 1458, James Douglas, lord Dalkeith, was to receive the name 'Morton' for his intended earldom, a protest was presented against this creation, asserting correctly that the lands of Mortoun belonged heritably to his step-grandmother, Janet Borthwick, widow of Sir James Douglas, known as 1st Lord of Dalkeith, and to her son William Douglas (progenitor of the Whittingehame branch of the Douglases), to which the Chancellor answered that "Lord Dalkeith was not to receive his title in the Earldom for the lands of Mortoun lying in the Lordship of Niddisdale but for the lands of Mortoun in the territory of Caldercleir".

[5] Morton reached Brechin, in Angus, where he signed a deed resigning his lands to his kinsman Robert Douglas of Lochleven, who was then compelled to resign the lands in turn to James V.[5] After James V's death in late 1542, George Douglas of Pittendreich and the Earl of Arran assisted Morton in reclaiming his lands, including Aberdour.

The heir apparent is the present holder's son John David Sholto Douglas, Lord Aberdour (b.