Green’s Dictionary of Slang

constr. with the, the hangman.

a.1705		Dorset ‘Song’ in Chalmers Eng. Poets VIII (1810) 345: The queen, overhearing what Betty did say, Would send Mr. Roper to take her away.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 212: Roper — the hangman — obsolete.