MYRMIDONS,
the Constable's Attendants, or those whom he commands (in the King's Name) to aid and assist him: Also the Watchmen.
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Entry taken from 1736 Canting Dictionary, by Nathan Bailey.
Myrmidons in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).