Plying their trade

Posted by KBo on February 27, 2008 at 22:46:

A two parter: 1- What is the origin of the phrase "plying their trade" and 2- I only remember hearing this in reference to prostitutes... are there limits to the type(s) of professions used with that phrase?

• Plying their trade Victoria S Dennis 28/February/08
  • Plying their trade RRC 28/February/08