Chapman is an itinerant salesman, touring the villages with his chap-bag full of needles and pins, lace, ribbons, small toys and simple books (chap-books).
A Badger was much the same, but tended to work in towns, where he had to apply for a badge to prove that he was an accredited door-to-door sales person, rather than just a mendicant.
The same name can also apply to a pauper on poor-relief, who also was made to wear a badge in some places.