I have never found anyone older than Robertus Dictus King. If you want info around the time of the family losing Barra try James King, wife Beatrice Liimsdaine, around 1580-1640, son of William King, son of James, son of William, son of James.
If you need info around 1600 try following the large amount of info on Sir James King, Lord Eythin 1589-1652. He was famous in the civil war.
I personally am interested in the James King of the Barra family that migrated to Corrard, Ireland in the early 1600's. There are so many James that it is confusing.