Green’s Dictionary of Slang

money; thus Stephen’s at home, one has money.

a.1790		H.T. Potter New Dict. Cant (1795).
1809		G. Andrewes Dict. Sl. and Cant.
1811		Lex. Balatronicum n.p.: stephen. Money. Stephen’s at home; i.e. has money.
1819		P. Egan Key to the Picture of the Fancy going to a Fight 19: The carman has gammoned it well [...] and has drawed all the steven.
1821		‘An Amateur’ Real Life in London I 556–7: The finder proposes, as he is rather short of steeven,* to swap his share for a comparatively small part of the value stated. [* Steeven—A flash term for money].
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 214: Steevin money, coined; and of silver is understood.
1832		Egan Bk of Sports 206: A winning man laughs at bruises, when he can pocket the steeven, and extend his fame.
1834		(con. 1737–9) W.H. Ainsworth Rookwood (1857) 258: For vere the odds are thus made even, / It plays the dickens with the steven.
1848		Flash Dict. in Sinks of London Laid Open.