Green’s Dictionary of Slang

billy n.6

[abbr. Billy Whizz n.]

(drugs) amphetamine.

[UK]N. Griffiths Grits 61: Larst fuckin month a sold off two ounces-a uncut billy.
[UK]N. Griffiths Stump 186: Poison? So’s all that fuckin bugle an billy yeh stick up yer snipe.