Green’s Dictionary of Slang

1. an untrustworthy, incompetent person, animal, action, circumstance, event.

c.1864		‘The Boarding School’ in Rakish Rhymer (1917) 54: She swore in future all who came, to know the right from the wrong ’uns.
1884		letter in Sporting Times 6 Sept. 3/1: At the late meeting of the York the Grand Stand swarmed with ‘wrong ’uns’. I counted five distinct gangs of lumberers .
1890		Bird o’ Freedom 1 Jan. 3/2: This — here she gave her snoring beau a dig under the fifth rib [...] — was a wrong ’un; drank and backed horses.
1901		B. Pain De Omnibus 134: Ah, she were a wrong un – a reg’lar right-darn wrong un!
1915		‘Bartimeus’ ‘A Captain’s Forenoon’ in A Tall Ship 55: The Master-at-Arms mentioned to me that a woman was at the bottom of it. She’s a wrong ’un, I understand.
1921		D.L. Sayers Unpleasantness at the Bellona Club (1977) 143: That awful female – I knew she was a wrong ’un.
1939		V. Davis Gentlemen of the Broad Arrows 37: You can bet a few wrong ’uns have heard about it.
1946		‘Josephine Tey’ Miss Pym Disposes (1957) 36: ‘If you mean a plain wrong-un, there was that dreadful creature who was man-crazy’.
1950		A. Christie Murder Is Announced (1958) 39: I made up my mind that he was definitely a wrong ’un.
1956		R.T. Hopkins Banker Tells All 39: I don’t say my old boss, Buzz Burns, the print dealer, was exactly a wrong ’un.
1989		T. Blacker Fixx 200: Her father’s a wrong ’un.
1999		N. Cohn Yes We Have No 304: She keeps falling in love, then finding she’s picked another wrong ’un.
2007		N. ‘Razor’ Smith Raiders 23: The hotel [...] had two ex-coppers working as hotel detectives [...] These two ‘yard dogs’, with their years of spotting a ‘wrong ’un’, had got Bob squarely in their sights.
2013		K. Sampson Killing Pool 212: Connolly has been a serious, consistent threat to public safety [...] preying on society [...] He’s a wrong ’un, Connolly, and no mistake.

2. a piece of counterfeit money.

1889		Notts. Guardian 24 Aug. 5/4: What a mug I must have been. I didn’t know the lils were ‘wrong ’uns’.
1890		‘Doss Chiderdoss’ ‘The Rejected’ Sporting Times 29 Mar. 1/3: For on tendering the money, the result was very funny — / They were wrong ’uns, and were everywhere rejected.
1899		C. Rook Hooligan Nights 36: Billy the Snide produced a wrong ’un.
1912		E. Pugh City Of The World 260: He’ll rig a ring of wrong ’uns on both sides o’ the pond.
1956		R.T. Hopkins Banker Tells All 11: When the cheque is discovered to be a ‘wrong ’un.’.

3. a prostitute.

a.1890

Bird o’ Freedom cited in Barrère & Leland Dict. Sl., Jargon and Cant 89/2: Wrong ’uns at the Wateries, Noffgurs at the Troc, [...] Coryphyees by Kettner, Tartlets anywhere.

4. a law-breaker, a criminal.

1890		Sporting Times 8 Mar. 2/1: There is a fine staff of detectives, and the thing to do would be to take one of them, say Shrives, whose knowledge of wrong ’uns is cosmopolitan, and make him chief.
1905		‘Doss Chiderdoss’ ‘Incredulity of Juries’ Sporting Times 18 Mar. 1/4: Though classified as ‘wrong ’uns,’ they were really great and good, / But they couldn’t get a jury to believe it.
1910		H.G. Wells Hist. of Mr Polly (1946) 187: You don’t look a wrong ’un. ’Ave you been to prison?
1933		J. Spenser Limey 16: The average gangster stares at all the world with insolent defiance. I am a ‘wrong ’un’ myself, but my eyes shoot straight.
1954		Oh Boy! No. 20 9: Why! Blake! I allus figured you for a wrong ’un.
1979		F. Norman Too Many Crooks Spoil the Caper 110: The wrong ’uns that’ve crossed my path lately would give a dedicated social worker a pain in the arse.
2000		J.J. Connolly Layer Cake 28: They’re getting grief from the local gathers who know they’re wrong ’uns and drive ’em mad.
2011		J.J. Connolly Viva La Madness 283: Might be from Bumfuck, Idaho, but she can spot a wrong ’un.

5. (UK Und.) a severe judge or magistrate.

1977

G.F. Newman Villain’s Tale 8: You scream the filth nicked your bit of dough. But you’re up the steps before a wrong ’un, you see what good it does you.