Green’s Dictionary of Slang

(Aus.) one who stages hold-ups and robberies.

1879		W.J. Barry Up and Down 197: They had only just been liberated from gaol, and were the stickers-up, or highwaymen mentioned.
1890		Dead Bird (Sydney) 1 Feb. 2/1: ‘Well, by — ’ replied the sticker-up, ‘you may follow, but you will never catch up to him on that horse’ .
1898		E.E. Morris Austral Eng. 438/1: Sticker-up, n. a bushranger.