The Galbraiths were an ancient family of the Lennox. Their name is Gaelic for 'Lowland Briton'. The article from I.M.M McPhail's Lennox Lore on Old Lennox Families comments:
"There is an old Gaelic saying about them:
Bhreatannach o'n Talla Dheig, Ualisle shliochd Albann do shloinn.
Galbraith of the Red Hall, Noblest of Alban's race, thy pedigree.
The Red Hall was said to be at Dumbarton Castle Rock 'on the south side thereof'. The prevalence of the name Arthur in the family in the early records and the bears' heads on their coat-of-arms both testify, if not their descent from a Briton, Arthur, at least to their belief in such a descent." Thus this also lends weight to the theory that King Arthur was Scottish and had a base at Dumbarton; the bear being a frequent epithet for King Arthur. As already mentioned Garscadden is probably the site of one of King Arthur's battles.
In 1208, one Gillescop Galbraith witnessed a charter by Alwin, Earl of Lennox. He appears to have been the Earl's nephew, mentioned as 'nepote nostro'. There are other mentions of charters of Galbraiths. The next Earl of Lennox, Maldowen, was to grant the Galbraiths various lands in the Lennox. A Gillespec Galbraith witnessed the grant of Colquhoun to Umfridus de Kilpatrick in 1244.
Sir William Galbraith, the fourth chief, married a daughter of the Black Comyn, becoming a co-regent of Scotland in 1255. Later a branch became the armour bearers of the Erskines and one Patrick Galbraith was bequeathed the lands of Garscadden, probably in lieu of service.
They held Garscadden till 1611 when Matthew Wallace of Dundonald bought the lands from Walter Galbraith. This marked a fall from grace for the clan and is a good indication of the financial troubles of the family. The seventeenth chief, Robert Galbraith, attempted to murder his brother-in-law rather than pay back his borrowings. He also tried to attack the chief of MacAulay, using the MacGregor clan; the chief's only misfortune being a marriage to Galbraith's widowed mother. Finally Galbraith was declared a rebel and fled to Ireland c. 1642. The clan chieftainship ended with his son and still lies vacant.