Green’s Dictionary of Slang

long tail n.1

a native of Kent.

[UK]Mercurius Fumigosus 26 22-30 Nov. 7: An Essex Calf [...] chansed not long since to tumble down the hill among the languine Dragonians at Temple-Barr, who being accompanied with a Kentish Long-taile [...] brought with them an Innocent Lamb, whom they had prepared for the slaughter, intending to cut his throat with a ten-shillings Knife.