A couple of my song-books give a bit of info--The song doesn't refer to the drums of the garrison of Dumbarton on the Clyde, but to a British regiment, which took its name from the officer who first commanded it, i.e. the Earl of Dumbarton. He was a cadet of the family of Douglas, who was commander of the Royal Forces in Scotland during the reigns of Charles II and James II; with the lost cause of the Stuarts, he left the country and died in exile in France in 1692. Further on this, I might as well summarise the entry in William Anderson's biographical book "The Scottish Nation" (1868), II.72: Title "earl of Dumbarton" conferred 1675 on Lord George Douglas, 3rd son the the first Marquis of Douglas. In his young days he was page of honour to Louis XIV of France, and became an officer in the French army (rose to be major-general). After the Treaty of Nimeguen (1673), recalled to England by Charles II, who created him Earl of Dumbarton by patent (9 March 1675). On the accession of James VII [= James II] was appointed commander-in-chief of the Scottish forces, and defeated the Earl of Argyll's invasion (1685). After the "Glorious Revolution" of 1688 he accompanied King James to France, and was appointed one of his lords of the bedchamber at St. Germains, where he died.