Green’s Dictionary of Slang

1. a type of wagon.

c.1698

B.E. Dict. Canting Crew.

2. a coach travelling from the provinces to London.

1674		T. Blount Glossographia (2nd edn) n.p.: Caravan or Karavan [...] also of late corruptly used with us for a kind of Waggon to carry passengers to and from London.
1689		London Gazette No. 2450/4: A Fair easie going Caravan, with a very handsome Roof Brass Work, good Seats, Glasses on the sides to draw up, that will carry 18 Persons.

3. (UK Und.) a large sum of money, esp. when seen by thieves as potential booty.

c.1698		B.E. Dict. Canting Crew n.p.: Caravan, a good round Sum of Money about a Man, and him that is Cheated of it.
1725		New Canting Dict.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
c.1750–1882		B.M. Carew Life and Adventures.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1835		G. Kent Modern Flash Dict.
1848		Flash Dict. in Sinks of London Laid Open.
c.1850		Duncombe New and Improved Flash Dict.
1859		Matsell Vocabulum.

4. the victim of financial fraud.

1676		Etherege Man of Mode III iii: third man: What spruce prig is that? first man: A caravan lately come from Paris.
1688		T. Shadwell Squire of Alsatia III i: As substantial bail as can be wished, for the redemption of our Suffolk caravan.
c.1698		see sense 3.
1725		New Canting Dict.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict.
1785		Grose Classical Dict. of the Vulgar Tongue.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1889		(ref. to late 18C) Gent.’s Mag. June 598: Towards the end of the century [xvii] a person easily gulled or bubbled was known as a ‘caravan,’ but earlier the term ‘rook,’ which is now restricted to a cheat or sharper, appears to have been applied to the person cheated [F&H].

5. a police van for conveying prisoners.

c.1828

‘New Version of Adam & Eve’ in Holloway & Black II (1979) 221: An every thief, or boy or man, sir, / Has a ride in a Caravan, sir.

6. a railway train, esp. when chartered by prize-fight attendees.

1864, 1867, 1870		in Hotten Sl.
1873		Sl. Dict. 108: Caravan, a railway train, especially a train expressly chartered to convey people to a prize fight.
1895		Crowe Aus. Sl. Dict. 15: Caravan, a train conveying people to a prize-fight.