drinking voucher; green drinking voucher noun a currency note, especially a £1 note UK Jocular.
[They buy] each other a drink and pay for it with greenies, crispies, lottery tickets, drinking vouchers. — Ann Barr and Peter York, TheOfficial SloaneRangerHandbook, p. 117, 1982
The owner counted out nine quid in the old “green drinking voucher” folding money. — Stuart Maconie, CiderwithRoadies, p. 125, 2003