The Barony of Barnes was erected by George Seton, 7th Lord Seton, for his third son, John.  Sir John Seton of Barnes was educated both in Scotland, France and Italy before finally proceeding to Spain.  He was born in 1553, and has been described as a brave man, well travelled and educated.  He was brought up at the court of King Philip II of Spain and rose to become a knight of the Kings personal bodyguard and master of his Household.  So distinguished was he that he was summoned home by King James VI & I.  He was given the office of Treasurer, as well as Master of the Horse, and Master of the Kings Household for life, and was proprietor of Hailes Castle and that of Garleton Castle while he waited for his Castle at Barnes to be built.  In 1588 he was admitted an Extraordinary of the College of Justice, though he died only a few short years later, and his Castle of Barnes was never completed.  Later, this branch assumed the title of the Earl of Dunfermline, forfeit.

Sir John Seton was proprietor of most of the land around Aimsfield.  He died in 1594 and was buried in the nave of the old church of Haddington, where now a grand carved monument can be seen in the Seton's of the Barnes' burying place. The farm of Amisfield Mains, formerly called Harperdean Mains was originally two farms.  The west part of it was called The Barnes. Amisfield Mains formed part of the estate of Seton of the Barnes.