Green’s Dictionary of Slang

1. leading pickpockets whose dress reflects their success (as well as facilitating their entry into the wealthy world on which they prey); thus swell-mob man, an individual pickpocket; also attrib.

1829		see sense 2.
1831		Satirist (London) 17 July 115/2: A gentleman [...] was attacked last week, in broad day, by a large and well-organised gang of the ‘swell mob,’ and eased of his purse in a most scientific style.
1835		Northampton Mercury 17 Oct. 4/4: The ‘cross-byters’ seem [...] to have likened more to the swell-mob man of the present day than to the ‘coney-catcher’.
1838		Caledonian Mercury 10 Sept. 4/3: He had succeeded in putting himself in communication with Mr Fogle Hunter and other gentlemen connected with the swell mob.
1840		R.B. Peake Devil In London II iii: peg: Oh, John, look at the beautiful carriages [...] full of gentlemen with cigars and moustachios. john: Only some of the swell mob.
1840		London Mag. Feb. 13/1: [A] very splendaciously attired individual, whom he naturally took for a swell-mob-man.
1845		Nat. Police Gaz. (NY) 1 Nov. 83/3: The man figured in London [...] as one of the leaders of the swell mob, and was considered as the best ‘screwsman’ and ‘fitter’ in the mteropolis, but was finally ‘served’ with a term in Botany Bay.
c.1850		Peeping Tom (London) 1 4/3: the swell’s guide [...] A curious specimen of the Flash Patter [...] Dialogue between a Shickster and a Goniff — Between a Swell Mob’s-Man and a Fogle Hunter.
1852		G.C. Mundy Our Antipodes I 94: This very ‘swell’ member of the swell mob was transported for robbing his Majesty’s mail.
a.1854		‘Cuthbert Bede’ ‘Æger’ in College Tales (1893) 223: The old gent’s vun o’ the swell mob.
1859		Belfast Morn. News 25 July 3/2: The Swell Mob in Belfast — some of these gentry did a tolerable business during the show.
1861		H. Mayhew London Labour and London Poor IV 307/2: The swell-mob are to be seen all over London, in crowded thoroughfares, at railway stations, in omnibuses and steamboats.
1868		Sportsman 14 Mar. 2/1: Notes on News [...] [A] gang of female swell-mob thieves—a Mrs Helen Pope, just arrested in Paris, with twelve more of her London light-fingered friends.
1872		G.P. Burnham Memoirs of the US Secret Service 199: A resort well known to the police as a halting-place for prominent English thieves, high Tobey-men, and members of the swell mob.
1885		Bulletin (Sydney) 18 Jul. 18/3: Now, among the London ‘swell mob’ and the ‘mug-catchers’ who infest English racecourses there are many staunch teetotallers and non-smokers.
1895		Crowe Aus. Sl. Dict. 83: Swell Nob [sic], a well dressed thief acting the gentleman.
1904		Number 1500 Life In Sing Sing 257: Swell Mob. Expert pocket thieves.
1910		J. Sullivan ‘Criminal Sl.’ in Amer. Law Rev. LII (1918) 889: A gang of three or more pickpockets who travel together is called a ‘mob.’ A ‘swell mob’ is a gang that can hire first-class legal talent and have good financial backing.
1924		G. Henderson Keys to Crookdom 411: Swell mob – prosperous gang of dips.
1949		Monteleone Criminal Sl. (rev. edn).

2. a major criminal gang, irrespective of their specialities; also attrib.

1830		Morn. Chron. 6 Mar. 4/2: He has been engaged in almost all the ‘out-and-out’ ramps which have been committed in the last ten years in the Metropolis; [...] he may be pronounced the Captain of the ‘swell mob’.
1831		Australian (Sydney) 9 Sept. 3/3: The class of London thieves who in slang language are designated the ‘swell mob,’ have followed in the wake of royalty, and have mustered in considerable numbers at Brighton.
1833		N.-Y. Daily Advertiser 12 Dec. 2/3: He was proved however to have been one of the swell mob of London, and known to the Bow street officers as a notorious thief.
1836		Marryat Mr Midshipman Easy I 185: A man who has belonged to the swell mob is not easily repulsed.
1849		Paul Pry 1 Jan. n.p.: Paul regrets to say he found himself surrounded by so many of the ‘swell mob,’ ‘gents of the turf,’ and ‘gentlemen of the ring’.
1850		New Eng. Washingtonian in Leics. Mercury 26 Jan. 4/5: There are [...] a large number of young men who lack every attribute that distinguishes the good citizen. [...] They have been known during the past few years various names—the swell-mob, soap-locks, &c. ; but, last a generic name for the whole class has been hit upon, and they have been christened ‘b’hoys’.
1873		J. O’Connor Wanderings of a Vagabond 311: None o’ yer blarsted swell-mobs broke up the ring then if their coves couldn’t win, none o’ yer bloody duffers wus chosen fur referees; but blooded gentlemen, the first hin the land, who’d see the best man win.
1882		Bristol Magpie 14 Dec. 14/2: ‘Not to-night I think, unless I wish to have “swell-mob,” ha! ha ! flung in my teeth again’.
1894		G.A. Sala London up to Date 86: Charley Lightfingers, popularly known in swell-mob circles as ‘Nickemquick’.
1914		Wash. Post 11 Nov. Misc. 3/4: Gone is the time when the ‘swell mob’ went out on the road or ‘derrick’ as they called it.
1921		P. & T. Casey Gay-cat 62: He said he did peter-pork, knew most o’ the swell mobs in Louie and York and Chi.
1931		W.N. Burns One-Way Ride 57: That’s a swell mob to be sticking up a good American bank.
1936		H. Corey Farewell, Mr Gangster! 280: Slang used by English criminals [...] Swell mob – well-selected and trained mob.
1949		Monteleone Criminal Sl. (rev. edn).
2000		J.J. Connolly Layer Cake 102: His outfit have sent him up to work out a deal with the smug Swell Mob and they’ve talked to him like he’s a fuckin teabag, a wanker.

3. attrib. use of sense 2.

1829		Globe (London) 13 Apr. 4/3: Upon inquiry. found he was one the ‘swell mob’ thieves, and is one of the most active robbers at the theatres.
1842		Western Times 20 Aug. 3/3: If he be a swell-mob man, he visits our markets [and] he happens to dip his fingers [...] into some justice’s daughter’s pocket.
1866		Night Side of N.Y. 60: The men who who come swaggering or sneaking in, are all got up in the most approved ‘swell-mob’ style with flashy waistcoats and neckties.
1869		J. Greenwood Seven Curses of London 119: An oft-convicted scoundrel of the ‘swell mob’ tribe.
1891		G.R. Sims ‘The Magistrate’ Dagonet Ditties 129: He saw him try / The pockets of ladies walking by, / And pass the swag to a swell-mob mate.