Green’s Dictionary of Slang

buffer n.1

[SE buff, the skin; see 1818 W. Parry London Guide 92: The term buffer derived from the pratice which once prevailed of carrying Bandanas, Sarsnets, French stockings, &c., next their shirts; so, as they were obliged to undress in order to come at the goods, or in other words, to strip to the skin or buff they obtained the name of buffers]
(UK Und.)

1. a villain who kills healthy horses and sells the skins; also a dog-thief.

[UK]B.E. Dict. Canting Crew n.p.: Buffer, c. a Rogue that kills good Horses, only for their Skins, by running a long Wyre into them, and sometimes knocking them on the Head, for the quicker Dispatch.
[UK]New Canting Dict.
[UK]Bacchus and Venus n.p.: Buffer, a rogue that killed good sound horses for the sake of their skins, by running a long wire into them [F&H].
[UK]Bailey Universal Etym. Eng. Dict.
[UK]B.M. Carew ‘The Oath of the Canting Crew’ in Farmer Musa Pedestris (1896) 51: No ballad-basket, bouncing buffer, / Nor any other, will I suffer.
[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: buffer, one that steals and kills horses and dogs for their skins.
[UK]Lex. Balatronicum.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.
[UK]G.W.M. Reynolds Mysteries of London I.
[UK]Hotten Dict. of Modern Sl. etc. 13: In 1737, a buffer was a ‘rogue that killed good sound horses for the sake of their skins, by running a long wire into them.’ — Bacchus and Venus.
[UK]Hotten Sl. Dict.
[UK]Sl. Dict.

2. (also buffor) a villain, specializing in selling supposedly smuggled goods; thus buff it, to peddle such articles.

[UK] ‘Come All You Buffers Gay’ in Farmer Musa Pedestris (1896) 52: Come all you buffers gay, / That rumly do pad the city.
[UK]W. Perry London Guide 2: Fellows who hang about in inn yards [...] selling and buying some article [are] called ‘Duffors or Buffors’.
[UK]W. Perry London Guide 91: Buffers [...] are invariably north-country-men. Jordaine was a Glasgow man and made ten thousand pounds [...] but never buffed it in the streets of London.
[UK]‘An Amateur’ Real Life in London I 169: Buffers miscalled Duffers—[...] go about from house to house, and attend public-houses, inns, and fairs, pretending to sell smuggled goods.
[UK]Comic Almanack Feb. 47: Come, buffers and duffers, and dashers and smashers.
[US] ‘Hundred Stretches Hence’ in Matsell Vocabulum 124: And where the buffer, bruiser, blowen, / And all the cops and beaks so knowin’.
[US]Plymouth Wkly Democrat (IN) 5 Jan. 1/5: Horse jockies, horse thieves [...] buffers, bummers [...] bravos and panderers [...] bludgenors, bounty jumpers, koniackers, knucks [and] pocketbook stuffers.