Green’s Dictionary of Slang

petty thieves, who take anything they can lay their hands on.

1714		A. Smith Lives of Most Noted Highway-men, etc. I 242: Them, who are termed St. Peter’s Children, as having every Finger a Fish-hook.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Fidlam ben, general thieves, also called St. Peters sons having every finger a fish hook (cant).
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.