Green’s Dictionary of Slang

ferreting n.1

[ferret n.1 (1) + sfx -ing]

(UK Und.) a confidence trick that involves the offering of spurious credit and the subsequent profitable dunning of the victim who has taken it.

[UK]Dekker Lanthorne and Candle-Light Ch. 3: Of Ferreting: or the Manner of vndooing Gentlemen by taking vp of commodities.