Green’s Dictionary of Slang

(UK Und.) half-a-crown, 2s 6d (12.5p).

c.1698		B.E. Dict. Canting Crew n.p.: Trooper c. a half Crown.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
c.1750–1882		B.M. Carew Life and Adventures.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1809		G. Andrewes Dict. Sl. and Cant.
1821		Flash Dict.
1835		G. Kent Modern Flash Dict.
1848		Flash Dict. in Sinks of London Laid Open.