In the children's renowned tongue twister, which was first published in London 1813, we learn
Peter Piper picked a peck of pickled peppers.
A peck of pickled peppers Peter Piper picked.
If Peter Piper picked a peck of pickled peppers,
Where's the peck of pickled peppers Peter Piper picked?
It seems that Peter picked the equivalent of 9 kg of fresh peppers (a peck) that were either destined to be pickled or perhaps he took the pickled delicacy from a vat.
Could it be that Peter stole the pickles? Etymonline says the verb pick took on the sense of “to rob, plunder” which was later watered down to “steal petty things, filch or pilfer from” by the late 14c.
Were capsicum peppers grown in England? Perhaps they were a well-known delicacy imported to England? I searched in Google Books for the recipe of pickled peppers in the 19th century and found very few references, and from what I could tell they were all by American cooks. The earliest reference I could find is from the American The Valley Farmer- Page 405 printed in 1854
EDIT
I found an earlier recipe dated 1850, from a book entitled Practical Cook Book Containing Upwards of One Thousand Receipts… by Mrs Bliss, a Bostonian.
PEPPERS
Pick the peppers late in the season, just before they begin to turn red; soak them ten days in a strong brine of salt and water; then, if they have a good green color, remove them from the brine to clear cold water, in which let them soak twenty four hours; if they have not a good green color, they will get it by a scalding in the brine; drain them, and if you wish them very hot, pack them away whole in cold vinegar; if you wish them very mild remove their seeds–scraping them out through a slit cut in the side of each pepper and pack them in vinegar. They ought to be good pickles in eight weeks.
If Peter Piper picked a peck of pickled peppers, is there any evidence to suggest that children or readers in the 19th century would have understood Peter was a thief?
What type of peppers were pickled in 18th and 19th century England? I don't think Capsicum peppers were ever grown there.