The Duncans and the Robertsons, or Clan Donnachaidh, appear to have had the same origin. They were descended from the ancient Earls of Athole and took their name from the chief Donnachadh Reamhar or "Fat Duncan" who led the clan at the battle of Bannockburn. The subsequent history of the Duncan's descendants is more properly given under the Clan Robertson, named after Duncan's great grandson, Robert, but here is outlined the history of the Duncans in the east of Scotland and represented by the family Duncan of Lundie in Forfarshire.

The Duncans possessed lands in Forfarshire, including the barony of Lundie and the estate of Gourdie. Sir William Duncan was one of the physicians to George III, and in 1764 was created a baronet, but the title became extinct on his death in 1774.

Alexander Duncan, of Lundie, provost of Dundee, was a royalist during the Jacobite rising of 1745. He married Helena, daughter of Haldane of Gleneagles, and their second son, Adam, born in 1731, entered the navy in 1746, and in 1780 he defeated the Spanish at Cape St. Vincent. In 1795 he was appointed commander of the fleet in the North Sea and Admiral of the Blue. He had blockaded the Dutch fleet for two years when the mutiny at the Spithead and Nore spread to all his own ships except the Venerable, his flagship, and the Adamant. By a stratagem he kept the Dutch in the Texel, and in 1797 he gained at Camperdown, one of the most glorious victories in the history of the British Navy. For his services he was created Earl of Camperdown by William IV, in 1831.

When George A.P. Haldane, 4th Earl of Camperdown, died in 1933, without issue, the earldom became extinct.

Crest: On waves of the sea, a dismasted ship