Green’s Dictionary of Slang

1. (UK Und., also tweedling) the substitution of fake jewellery for the real thing, usu. by sleight of hand in a jewellery store, esp. in the form of a tweedle, a fake ring studded with paste diamonds.

1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant II 383/2: Tweedle (thieves), a spurious ring, used to swindle jewellers and pawn brokers .
1925		E. Jervis 25 Years in Six Prisons 17: ‘Tweedling’ [...] is this: You buy a real, genuine eighteen-carat-gold watch-chain for about twelve pounds; and also a few of those made in Birmingham [...] The chain is handed over in the tissue-paper, and the ‘tweedler’ departs. But it was the Brummagen chain that the ‘can’ got.
1938		F.D. Sharpe Sharpe of the Flying Squad 275: One of the oldest methods of crime is the Tweedle. [...] The Tweedler spots a ring worth a lot of money in a jeweller’s shop and goes to great pains to have an exact though worthless replica made. He goes in, asks to see the tray containing the ring, and when the assistant isn’t looking very carefully susbstitutes the fake for the real thing.
1941		V. Davis Phenomena in Crime 256: The tweedle. Changing a spurious ring or gold watch for a dud one.
1959		J. Gosling Ghost Squad 116: The original tweedle [...] has its setting in a public house. The place is carefully chosen for the landlord and his wife, who must have a liking for jewellery.
1989		(con. 1950s–60s) in G. Tremlett Little Legs 198: tweedle a deception, often involving the substitution of phoney items like rings or jewellery for the real thing.
1998		J. Hoskison Inside 62: ‘What’s the tweedle?’ [...] ‘You buy something cheap like a ring from Woolworth’s, go to a jeweller’s and ask to see a tray with something similar on it. Then your partner comes in, makes a distraction, and you swap the crap for a bit of pucker “tom”.’.

2. the sale of any dubious goods; thus as v., to sell dubious goods.

1956		‘Charles Raven’ Und. Nights 186: His principal war-work, however, was the whisky tweedle and the barge-wharf.
1981		(con. c.1910) A. Harding in Samuel East End Und. 184: He ‘had to tweedle’ as we used to say – that is, he acted as a go-between for diamond stealers and their customers.
1989		(con. 1950s–60s) in G. Tremlett Little Legs 10: Working the knocker, totting, or doing the tweedle and the twirl.