RUM-Duke,
a jolly handsome Man, Rum-Dukes, the boldest or stoutest Fellows (lately) amongst the Alsatians, Minters, Sawyards, &c. sent for to remove and guard the Goods of such Bankrupts as intended to take Sanctuary in those Places.
Rum Duke in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).