Green’s Dictionary of Slang

file n.

[ety. unknown; despite chronology OED suggests abbr. foil-cloy n., thence file-cloy under file v.1 . Weekley, Etymological Dict. of Modern English (1921), offers link to Fr. filou, a pickpocket; DSUE suggests SE file, a metal tool used to cut through things, and file, a rascal; 18C Fr. argot also has filer doux, to flatter, wheedle, ‘play the sleeping dog’, i.e. lie in wait]
(UK Und.)

1. a pickpocket.

[UK]Wandring-Whores Complaint title: A full discovery of the whole Trade of [...] Bawds, Whores, Fyles, Culls, Mobs, Budges, Shop-lifts, Glasiers, Mills, Bulkers, [...] and all other Artists, who are, and have been, Students of Whittington Colledge.
[UK]Head Canting Academy (2nd edn) 28: A whole gang of rogues, distinguished by Files, Lifts, Gilts, Budges, Runners, Heavers, &c.
[UK]A Newgate ex-prisoner A Warning for House-Keepers 6: A File is a Pickpocket, a Bulk is his tame-Rogue, who goes alwaies with the File, for he can do nothing without the File.
[UK]B.E. Dict. Canting Crew n.p.: File, c. a Pick-pocket.
[UK]N. Ward Hudibras Redivivus II:5 16: Jilts, Shoplifts, Files and brimstone B—s.
[UK]C. Hitchin Conduct of Receivers and Thief-Takers 14: It was my Opinion they were inclinable to turn Files, (alias Pick-Pockets).
[UK]J. Dalton Narrative of Street-Robberies 28: As to Hulks, Finebones, Black Isaac, &c. they were but Under-strappers, tho’ Black Isaac could Bite a Clout, as dexterously as any File in Town.
[UK]Bailey Universal Etym. Eng. Dict. n.p.: A file, or Bungnipper, Pick-pockets, who generally go in Company with a Rogue, called a Bulk or Bulker, whose Business ’tis to jostle the Person against the Wall, while the File picks his Pocket; and generally gives it to an Adam Tiler, who scowers off with it.
[UK]Life and Character of Moll King 12: harry: But who had you in your Ken last Darkee? moll: We had your Dudders and your Duffers, Files, Buffers, and Slangers.
[UK]Scoundrel’s Dict. 18: Partners to Files – Shoulder-shams. [Ibid.] 29: The File is the same as the Diver, tho’ for the most part he goes without the Bulk, and was formerly known by the Title of the Bung-nipper, because of a horn Thumb and sharp Knife, he used to cut the Pockets clean off, with all that was in them.
[UK](con. 1710–25) Tyburn Chronicle II in Groom (1999) xxvii: A File A Pick-pocket.
[UK]Grose Classical Dict. of the Vulgar Tongue.
[UK] ‘The Bowman Prigg’s Farewell’ in Wardroper (1995) 283: Then aideu to all kins and knots, / To kid-layers, files and trapanners.
[UK]Vaux Vocab. of the Flash Lang. in McLachlan (1964) 240: File, in the old version of cant signified a pockpocket, but the term is now obsolete.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.
[US]Matsell Vocabulum 32: file A pick-pocket. The file is one who is generally accompanied by two others, one of whom is called the ‘Adam tyler;’ and the other the ‘bulker,’ or ‘staller.’.
[UK]Hotten Dict. of Modern Sl. etc. (2nd edn).
[UK]Sl. Dict.
[US]Irwin Amer. Tramp and Und. Sl. 72: File.–A pickpocket.
[US]Monteleone Criminal Sl. (rev. edn).

2. a shoplifter.

[UK]J. Poulter Discoveries (1774) 29: To caution all Shopkeepers and Salesmen against Shoplifters of both Sexes [...] There shall be generally three Persons together, called in Cant Prigger Lifts or Files [...] They will open a Piece of Stuff and hold it up between the Owner and their Partner that sits down with her Petticoats half up ready for the Word nap it; then she puts it between her Carriers (that is, a Cant Word for Thighs) and then gets up and lets her Clothes drop [...] and so walks off.

3. (also old file upon the town) an experienced fraudster or confidence trickster.

[UK]Vaux Vocab. of the Flash Lang. in McLachlan (1964) 240: file: a person who has had a long course of experience in the arts of fraud, so as to have become an adept, is termed an old file upon the town; so it is usual to say of a man who is extremely cunning, and not to be over-reached, that he is a deep file.
[UK]‘An Amateur’ Real Life in London I 141: †Old files—A person who has had a long course of experience in the arts of fraud, so as to become an adept in the manoeuvres of the town, is termed a deep file—a rum file, or an old file.
[UK]Lytton Paul Clifford I 147: A middle-aged man, though a very old ‘file,’ who was sentenced for getting money under false pretences.
[UK]Morn. Post (London) 7 June 4/2: I find that he has lived upon the report of 25,000l. [...] its all nonsense. he is a regular old file upon the town.
[UK] ‘Fight with Snapping Turtle’ in Martin & Aytoun Bon Gaultier Ballads 65: The old experienced file [...] Answered with a quiet smile.
[UK]Thackeray Virginians I 188: Will is an old file, in spite of his smooth face.

4. an artful, cunning or shrewd person, a man, a ‘fellow’; thus old file, an old and/or experienced person.

[UK]W.T. Moncrieff Tom and Jerry II iv: Well, I’m off – you’re a good old file – I’ll give you a shilling for luck.
[UK]Egan Bk of Sports 160: Into the space tom ol— , the clever file, / Has stakd’ and rop’d, and made for boxer’s fit.
[UK]Westmorland Gaz. 9 Dec. 8/6: If you are a cunning old file [...] With money to rent and to buy land [...] Why, your fortune is made.
[UK]‘Epistle from Joe Muggins’s Dog’ in Era (London) 24 Jan. 4/1: [H]e’s a cunning old file, and chisels the green ones who want to sport their pound or two on a race beautifully.
[UK]R.S. Surtees Mr Sponge’s Sporting Tour 133: Frosty’s a cunning old file.
[UK]Essex Standard 28 Mar. 3/5: There were a few rum old files.
[UK]J. Greenwood Dick Temple I 57: ‘What kind of fellow is the cabman, Jack?’ ‘An old file, and well up to his work.’.
[UK]A. Day Mysterious Beggar 333: Oh you old snoozer! [...] Wouldn’t I mop th’ floor with ye! Ye ugly old file!
[UK]Sporting Times 13 Jan. 6/3: The knowing old file in Pretoria / Caught the ‘Stater’ with visions of gloria.
[UK]Marvel 9 June 552: He’s a decent old file, Frank, you know.

5. a pickpocket’s assistant.

[US]‘Ned Buntline’ Mysteries and Miseries of N.Y. I 13: Why, warn’t none of the files on the tramp?

In compounds

file-lifter (n.)

a pickpocket.

[UK]Partridge DSUE (1984) 390/2: ca. 1670–1800.

In phrases