E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Box Harry (To),
among commercial travellers, is to shirk the table dhôte and take something substantial for tea, in order to save expense. Halliwell says, to take care after having been extravagant. To box a tree is to cut the bark to procure the sap, and these travellers drain the landlord by having a cheap tea instead of an expensive dinner. To box the fox is to rob an orchard.