There seems to be two different origins of the Adair name. The "Edgar" Adairs and the "Fitzgerald" Adairs. The "Edgar" Adairs origins may be found in the volumes "Scot's Peerage" under : CRICHTON,LORD CRICHTON(page 53) vol... CRICHTON,EARL OF DUMPHRIES (page 218) vol.. DUNBAR,EARL OF DUNBAR(pages 240 etc.)
Crichton, Lord Crichton: "From a charter by King Robert I. to Richard Edgar, also supposed to be dated c.1320, of the manor place and one-half the barony of Sanchar, it appears that the other half of the barony pertained to William de Crechton and Isabella, his wife, as heirs-portioners with RICHARD EDGAR of the said barony.This lady is generally said to have been one of the two daughters of the last Ros or de Ros of Sanquhar, while the family of Edgar claim descent from her elder sister."
Earl of Dunbar lineage: Gospatric, towards the end of the year 1067 was made Earl of Northumberland by King William the Conqueror.In 1072 the Earl fled to the Court of his cousin, the King of Scots, and thence he sailed to Flanders.On his return King Malcolm gave to him Dunbar, with adjoining lands.He had a son Edgar. An Earl joined his kinsman King David I in his invasion of England in 1138, and commanded the men of Lothian at the battle of Cowton Moor, near Northallerton, otherwise called the battle of the Standard, fought on 23rd August 1138. He, or his descendant had the other half of Sanquhar.