Green’s Dictionary of Slang

1. (UK prison) one who initiates a new prisoner by robbing them of their possessions.

1830

Lytton Paul Clifford I 150: Messieurs the ‘rampers’ ceased from their amusements; and the ringleader of the gang, thumping Paul heartily on the back, declared he was a capital fellow, and it was only a bit of a spree like.

2. a swindler, usually on the racecourse .

1819		Sporting Mag. V 123: The cup-and-ball Macers, the Nob-Pitchers, and the Rampers.
1888		J. Runciman Chequers 7: A man who is a racecourse thief and ‘ramper’ hailed me affably.
1894		Mirror of Life 22 Dec. 7/3: ‘[R]ampers,’ prey upon the innocents who attend the various racecourses.
1895		C. Crowe Aus. Sl. Dict. 65: Ramper, a fellow who welches in summer and garrottes in winter.
1900		Sydney Sportsman (Surry Hills, NSW) 3 Oct. 1/1: Reach out for your pen and drive the rampers schlock-oh .

3. a street thug, a hooligan.

1873		Sl. Dict. 266: Ramper a ruffian of the most brutal description, who infests racecourses and similar places on welching expeditions during summer, and finds pleasure and profit in garrotte robberies during winter.
1885		Chambers’s Journal 28 Feb. 136: He is a ramper and bully to a couple of outside betting-men [F&H].
1890		Sporting Times 4 Jan. 6: Away from the ‘rampers’ we hurried.
1895		C. Crowe Aus. Sl. Dict. 29: Floorers, or Trippers, or Rampers, robbers who cause people to slip on the streets and then rob them.
1909		J. Ware Passing Eng. of the Victorian Era 206/1: Rampers (London Street). Noisy street-rangers, chiefly young men.