The Ker dynasty was founded by David Ker, a merchant of Ballymena, Co. Antrim, he held a lease on Robert Adair's mill at Ballymena c.1710 around this time he married Jean Boyd of Clontfinnan near Clough, also Co Antrim.

The couple had eleven children three of whom were to follow their fathers example and become merchants. William in Ballymena, Hugh in Dublin, their brother David settled in London and traded at Cateaton Street, first as Ker & Elmes, and after 1758 as David Ker & Co. In 1765 he purchased the Portavoe estate near Groomsport, in the Ards. After his death in 1770 he was succeeded by his son also David who in 1785 purchased the Clough and Magheraknock estates in Co. Down from Arthur Annesleu and in 1800 that of Montalto at Ballynahinch, Co. Down, from the 2nd Earl of Moira

David's brother, Richard Gervais Ker, bought the Red Hall estate at Ballycarry, Co Antrim, in 1780 from Sir Archibald Edmonstone. in 1781 he became high sheriff of County Antrim

David Ker died in 1811, and was succeeded by his son David, who in 1814 married the daughter of the 1st Marques of Londonderry and in 1834 bought the Southwell estate at Downpatrick, Co. Down, from the representatives of Lord de Clifford.