Green’s Dictionary of Slang

a covered cart in which travelling hawkers carried their goods around the country. It could be locked to secure the stock.

1812		Vaux Vocab. of the Flash Lang. in McLachlan (1964) 251: lock-up-chovey a covered cart, in which travelling hawkers convey their goods about the country, and which is secured by a door, lock, and key.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1833		H. Smith Gale Middleton 1 154: ‘We shall have the drag here presently.’ [...] ‘I hope he’ll bring a lock-up chovey’.
1871–82		B.M. Carew Life and Adventures.