Green’s Dictionary of Slang

(UK Und.) waiting in the street to waylay and rob waggons; thus waggon-layer, waggon-dodger, a waggon thief.

1703		Hell Upon Earth 3: Some are skillful at the Waggon-Lay.
1708		J. Hall Memoirs (1714) 5: Waggon-Layers, Such as wait just outside of Town for Waggons coming in or going out of Town in a Dark Morning, to take Boxes, or any Portable Bundles, out of them.
1718		C. Hitchin Conduct of Receivers and Thief-Takers n.p.: The Waggon-Lay alias to steal out of Waggons upon the Road.
1768		(con. 1710–25) Tyburn Chronicle II in Groom (1999) xxvii: The Waggon Lay Stealing Goods out of Waggons at an Inn, or on the Road.
1786		Whole Art of Thieving n.p.: The waggon and coach lay stealing out goods as they pass along.
c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Waggon Lay. Waiting in the Street to Rob Waggons going out of or coming in to Town commonly in the Dartk.
1796		Grose Classical Dict. of the Vulgar Tongue (3rd edn).
1818		W. Perry London Guide 110: waggon dodgers. Fellows who follow after town carts, and such like to pick up any portable package that may remain unprotected for a moment [...] I have seen a couple of them dodge a waggon from Piccadilly to the city, in order to dislodge a poorish-looking box.