Green’s Dictionary of Slang

money, thus as v. to pay.

1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 8: Poppy: To pay debt.
1943		Police Jrnl 16 69: Poppy, money [OED].
1959		A. Wesker Roots I 29: How’s poppy? [...] Tight as ever.
1977		D. Powis Signs of Crime 197: Poppy Money.
1986		J. Sullivan ‘From Prussia With Love’ Only Fools and Horses [TV script] As soon as Boycie weighs in with the poppy I’m going straight down the bureau de change.
1993		I. Welsh Trainspotting 15: Partin wi that poppy wis the hardest bit.
2012		(con. 1980s) I. Welsh Skagboys 35: Just fuck oaf and tour aroond till the poppy runs oot.
2013		T. Black Ringer [ebook] n.p.: Monique will be getting the jotters sometime round about the third or fourth week [...] and it can fucking whistle if it thinks I’ll be handing over any of this poppy either.
2020		G. Armstrong Young Team 7: His maw n da huv git a wee bit ae poppy tucked away.