Green’s Dictionary of Slang

enin yeneps n.

nine pence.

1859		Hotten Dict. of Modern Sl. etc. 126: ENIN YENEP, ninepence. [Ibid.] ENIN YANNOPS, or yeneps, ninepence.
1860		Hotten Dict. of Modern Sl. etc. [as cit. 1859].
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 23/1: Enine-yenep .... Ninepence.
1873		Sl. Dict.
1935		R.T. Hopkins Life and Death at the Old Bailey 65: Costermongers invariably use the following terms in discussing money transactions [...] Enine-yenep – Ninepence.