knight of the grip

A commercial traveler; a drummer. *knight of the post, s. A knight dubbed at the whipping-post or pillory; one who gained his living by giving false witne ; a false bail; a sharper, a swindler. "Whene'er we meet wi' fellows who hire knights of the post in law-suits and rascals who forswear themselves." Echard: Plautus (1694), p. 151.