Green’s Dictionary of Slang

a robber with violence.

1851		Bell’s New Wkly Messenger 9 Mar. 6/2: The cracksman and the rampsman constitute [...] the thieves’ aristocracy. there being usually a certain amount of courage required.
1856		H. Mayhew Great World of London I 46: Those who plunder with violence [...] ‘rampsmen,’ who stop people on the highway.
1861		H. Mayhew London Labour and London Poor IV 25: those who plunder with violence [...] 2. ‘Rampsmen,’ or Footpads.
1873		Sl. Dict.
1882		Sydney Sl. Dict. (2 edn) 7: Rampsmen - Burglars, highway robbers.
1976		(ref. to mid-19C) R. Sabbag Snowblind (1978) 31: What Swan was engaged in here [...] was a very famous and time-honoured flim-flam – in the slang of the Victorian London rampsman, it was affectionately known as the fawney-drop.