Green’s Dictionary of Slang

counterfeit.

1818		W. Perry London Guide 69: The found money is counterfeit, or screens, or else Fleet notes.
1821		‘An Amateur’ Real Life in London I 555: The purse of course is found to contain counterfeit money—Flash-screens or Fleet-notes.
1833		J.S. Burn Hist. Fleet Marriages n.p.: Many of the early Fleet parsons and tavern-keepers in the neighbourhood fitted up a room in their respective lodgings [...] as a chapel.