BLACK-GUARD,
dirty, nasty, tatterred roguish Boys, that formerly were wont to attend at the Horse-Guards to wipe Shoes, and clean Boots.
dirty, nasty, tatterred roguish Boys, that formerly were wont to attend at the Horse-Guards to wipe Shoes, and clean Boots.
Entry taken from 1736 Canting Dictionary, by Nathan Bailey.
Black Guard in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).