Green’s Dictionary of Slang

1. a book; a pocket-book or wallet.

1812		Vaux Vocab. of the Flash Lang.
1821		D. Haggart Autobiog. 16: We determined [...] to look out for a good stake, and content ourselves with one or two rum lils, if they could be had.
1833		‘The Slap-Up Cracksman’ in Swell!!! or, Slap-Up Chaunter 43: So flick the suck — or draw the clicks, / The lil, the jam, or bung from kicks.
1848		Flash Dict. in Sinks of London Laid Open.
1859		Matsell Vocabulum.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.
1895		C. Crowe Aus. Sl. Dict. 45: Lil, a pocket-book.

2. a £5 note.

1889		Notts. Guardian 24 Aug. 5/4: What a mug I must have been. I didn’t know the lils were ‘wrong ’uns’.
1890–1904		Farmer & Henley Sl. and Its Analogues.

3. (UK Und., also crook lill) a forged bank note; thus lil-faker, a counterfeiter.

1859		Matsell Vocabulum.
1895		C. Crowe Aus. Sl. Dict. 45: Lill, a bad bill.
1909		Illus. Police News 3 Apr. 14/1: The Magistrate: What are bobby notes? . Mr. Armstrong: The witness knows, sir snide notes. [...] A bobby note is a Bank of Engraving note. Mr. Budden: The proper word for Bank of Engraving note is ‘lill’.
1912		Proc. Old Bailey 1 Dec. 🌐 He said, ‘Robinson could not make lils, leave alone bank notes.’ ‘Lils’ are flash ‘Bank of Engraving’ notes.
1925		E. Jervis 25 Years in Six Prisons 150: Manufacturers of ‘Bank of Engraving’ notes, which are known to the fraternity as ‘Lills’.
1928		Eve. News (Sydney) 5 May 4/5: In best burglar circles a Jemmy is known as a James. In sporting circles forged tenners are known as crook lills.
1929		C.G. Gordon Crooks of the Und. 33: I felt a trifle ‘windy’ when I produced the roll of ‘lills’. [Ibid.] 127: Here he would wave his hundred-pound note (invariably a ‘lill’ – a bank of Engraving note).
1956		(con. 1900s) R.T. Hopkins Banker Tells All 49: A ‘lil’ is a copy of a Bank of England note with the words Bank of Engraving substituted for Bank of England in order to evade the definite charge of forgery against the printer. [Ibid.] 126: As a rule the crook does not attempt to pass lils as ‘real money’. They are used in all kinds of sharp practices to impress those whom the crooks seek to fleece. [...] What has become of those shadowy individuals who were known to the police as lil-fakers, moskers and duffers?

4. any banknote.

1984

Partridge DSUE (8th edn) 684/2: C.20.

5. see lily n.