Green’s Dictionary of Slang

1. a pickpocket.

1895		J. Greenwood Behind A Bus 41: It made people who had money about them nervous and fidgety, and caused them to feel every minute or two that their purse was safe, thus giving the ‘dipper’ the tip where to fish for it.
1900		Bulletin (Sydney) 22 Sept. 28/1: Re that Sydney D.T. yarn [...] about the purse ‘dipper’ leaving a valuable diamond ring in the lady’s pocket.
1908		Truth (Brisbane) 12 Apr. 9/3: Dippers, has ’em workin for them / Keepin nixey awl around / (Them’s the blokes as picks your pockets, / When you’re mixed up In a crowd).
1910		Truth (Perth) 23 July 12/8: ‘Dippers’, praps I may inform you, / Are a name we gives to those / As gets dippin in folks pockets / For the purses in there close.
1924		H.L. Wilson Professor How Could You! 72: Any dipper that tries to frisk you will have his work cut out.
1946		S. Jackson Indiscreet Guide to Soho 118: Soho is the home of some of London’s slickest ‘dippers’ or ‘whizzers’ (pickpockets).
1962		K. Orvis Damned and Destroyed 37: Some dirty dip picked my pocket!
1976		R. Sabbag Snowblind (1978) 146: Number one – the pickpockets. Every dipper in the country is going to pack up and leave home.
1989		(con. 1982–6) T. Williams Cocaine Kids (1990) 102: Another less flamboyant group of habitués are those who make money through wit, skill, and guile: boosters (professional shoplifters), dippers (pickpockets) and con artists.
1990		J. Healy Streets Above Us (1991) 4: Buskers and charity collectors act unwitting pilot fish for the dipper sharks.
2004		London Posse ‘Money Mad’ 🎵 Could be a kiter, a dipper, a blagger.

2. see dip v.² (5)