Dunbartonshire Lieutenancy Dunbartonshire (Siorrachd Dhùn Bhreatainn in Gaelic) or the County of Dumbarton,'s a lieutenancy area and a registration county of Scotland. Until 1975 it was a county. The area had been previously been part of the historic district of Lennox, which was a duchy in the Peerage of Scotland, see Duke of Lennox. Name Dumbarton was formerly the county town, and the county was originally also spelled Dumbartonshire. By the 18th century the names "County of Dunba… (More on Dunbartonshire)