A “knowing fellow.” One who knows all the tricks and ways of London life, and profits by such knowledge.
The Artful Dodger. John Dawkins, a young thief, up to every artifice, and a perfect adept in villainy. A sobriquet given by Dickens to such a rascal, in his Oliver Twist, chap. viii.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894