A banner of the arms
held by the Earl of Lennox, an old Scottish province that included the town of Dumbarton might be a useful basis for a flag for the county. The arms came to be associated with the territory and were accordingly used by the Dunbartonshire County Council whose territory was virtually synonymous with that of the province of Lennox. Notably a red saltire is also used as its insignia
by the Dumbartonshire Golf Union.
The design is thus rooted in the local history and self-evidently a sensible suggestion to serve as inspiration for a county flag.