Green’s Dictionary of Slang

owt yeneps n.

two pence.

1859, 1860		Hotten Dict. of Modern Sl. etc.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 23/1: Owt-yenep ... Twopence.
1873		N.S. Dodge ‘Vagrants and Vagrancy’ in Appleton’s Journal (N.Y.) 6 Sept. 308: The main principle upon which this peculiarity revolves, is to spell and pronounce the substantives in any sentence backward. Yennep, in this way, stands for penny; owt-yeneps, for twopence.
1902		Worcs. Chron. 3 May 3/1: The rhyming slang for bread is ‘Lump o’ Lead’. The back-slang is ‘Da-erb’. I heard a man call out to another yesterday that his Rekab had put his da-erb up to owt yannep flatch.
1935		R.T. Hopkins Life and Death at the Old Bailey 65: Costermongers invariably use the following terms in discussing money transactions [...] Owt-yenep – Twopence.