Dunbar Douglas, fourth Earl of Selkirk, succeeded to the earldom in 1744. He was Lord Lieutenant of the Stewartry of Kirkcudbright. The Earl supported the government during the rebellion of 1745, and in 1770 took a prominent part in resisting ministerial influence in the election of Scottish representative peers.

Dunbar Hamilton was the grandson of Basil Hamilton a younger brother of Charles, the 2nd and John, the 3rd Earl. (The title of Ruglen, governed by completely different rules passed to John's daughter Anne Hamilton and thus pursued a separate history.)

Dunbar Hamilton, who changed his name to Dunbar Douglas when he inherited the title, had the misfortune of burying no less than six sons, but fortunately he had a seventh who was thus able to succeed him. His seventh son Thomas Douglas, 5th Earl of Selkirk was to become perhaps the most famous holders of the title.