Green’s Dictionary of Slang

confidence trickery, fraud; also attrib.

1821		Egan Life in London (1869) 378: The no-pinn’d hero, on being elevated, gave as a toast, success to flat-catching.
1830		Egan Finish to the Adventures of Tom and Jerry (1889) 244: She lives principally [...] by flat-catching!
1840		N.Y. Herald 15 Jan. 2/4–5: Flat catching. [headline] [...] before him stood the identical flat catchers, who it seems had tried the same game on Mr. W., with whom it was ‘no go’.
1848		‘Epistle from Joe Muggins’s Dog’ in Era (London) 17 Sept. 5/2: [T]he swells of the party doin the grand as smart as new sixpences, the ragged ‘uns at the old game of Flat-catching.
1852		Bell’s Life in Sydney 9 Oct. : [heading] Flat-Catching [...] he lost £60 of good and lawful current coin of the realm.
1855		Delhi Sketch Bk 1 May 50/1: Flirting, Courtship, Serious or deceitful, Interest, these are the efficient motives which influence the vast Ambition, Patronage, Speculation, Flat catching, Trout majority both of givers and goers.
1869		J. Greenwood Seven Curses of London 386: It would be amusing to peruse the various styles of address [...] and to mark the many kinds of bait that are used in ‘flat-catching’ as the turf slang has it.
1884		Sporting Times 22 Nov. 1/5: ‘And which kind of sport [...] do you prefer—flat racing or steeplechasing?’ ‘Flat-catching,’ replied the Grumbler.
1888		Shields Dly Gaz. 28 Nov. 3/1: There is something really comic in a nice, simple, inexperienced young person [...] going out on a flat-catching expedition [...] the Conservative party was flat-catching when it took up the Fair Trade question.
1890		Morn. Bulletin (Rockhampton, Qld) 18 Jan. 6/3: That these worthies are engaged in the pastime known as ‘flat-catching’ there can be little doubt. Wherever they are the probability is they are running uuder assumed names.
1899		‘Pot’ & ‘Swears’ Scarlet City 351: When you go flat-catching again, take your street whispers to the chickens in Rotten Row.
1906		Sun. Times (Perth) 4 Feb. 1/1: A flat-catching firm offer an alleged Strad violin for sale at £3 10s [...] the possessor of a real Strad can get £1000 for it.
1919		J. Buchan Mr Standfast (1930) 698: You English [...] think a fellow’s a dandy at handling your Government if he happens to have made a pile by some flat-catching ramp on your Stock Exchange.