I read a book a while ago by Bill Cullen (a successful Irish businessman) called It’s a Long Way From Penny Apples - I wonder if that was it?
Anyway, I’ve found an earlier citation of “boxing the fox” in “Notes and Queries”. Its subtitle varies - something like “a medium of intercommunications for literary men, artists, antiquaries, genealogists, etc.,” published in London in 1849. Here‘s as much as I could make out from the quoted passage:
… the slang synonym for stealing fruit from an orchard. Is the term common to the puerility of the British Island; and if so, what is the meaning of the word “boxing”? W. A. Henderson. Dublin
Sadly, I can’t find the reply.
Edit: even earlier in 1844:
From The public and private life of lord chancellor Eldon, with selections from his correspondence … By Horace Twiss
I remember once being carried before a magistrate for robbing an orchard; ‘boxing the fox’ as we called it
The wiki page on Lord Chancellor Eldon:
John Scott was educated at Newcastle upon Tyne Royal Grammar School. He was not remarkable at school for application to his studies, though his wonderful memory enabled him to make good progress in them; he frequently played truant and was whipped for it, robbed orchards, and indulged in other questionable schoolboy freaks
I wonder if this suggests that the phrase was also used in the UK?