The vikings termed marsh dwellers "kjrr". When their descendants arrived in Britain from Normandy with William the Conqueror the term had become a name with the forms Ker and Kerr, also Carr and Carre.
From Arran on the Celtic West Coast comes a claim that the name is derived from the Gaelic for "strength".
Scottish records from the time of William the Lion mention John Ker, the hunter of Swinhope, but it was around 1330 that two brothers, Ralph and John, moved from Lancashire to Roxburgh to establish the principal Kerr families of Scotland. Ralph's descendants became the Kerrs of Ferniehurst, the senior branch, whilst John was progenitor of the Kerrs of Cessford.
The two powerful Borders families soon became rivals. The Kerrs were Crown vassals and collecting further influential positions whilst the Douglas families collapsed.
Andrew Kerr of Cessford aquired a charter to the barony of Old Roxburgh in 1451, becoming warden of the marches six years later. In 1502 the barony of Oxnam became Sir Andrew Kerr of Ferniehurst's by royal charter and he became warden of the middle marches.
Twelve years later this office was taken by a Kerr of Cessford, another Sir Andrew. His grandson, Mark Kerr, excelled in his aquisition of power becoming the first Earl of Lothian in 1606. The male line ended abruptly with his son's death in 1624 and the title failed.
Further Earldoms were bestowed on the families with Sir Robert of Ferniehurst becoming Earl of Ancram and Sir Robert of Cessford, by 1616 spelling his surname Ker, being created Earl of Roxburghe. The Earldom of Lothian was revived for the Earl of Ancram's son in 1631. This was the year that the family feuding ended thanks to the marriage of William Kerr ofFerniehurst and Ann Ker of Cessford.
Following support for the dubious Union with England in 1707, the Roxburghe title was raised to a dukedom. In 1805 the dukedom of Roxburghe, through female lines, was aquired in marriage by the chief of Clan Innes, who changed his name to Innes-Ker.
Although the mansion of Monteviot is the principle seat, the twelfth Marquess of Lothian, descendant of William and Ann, resides at Ferniehurst Castle.