either a Useful or Useless Piece of Information depending on your own point of view.
A Mop Fair was traditionally held on 12th October for the hiring of servants for the coming year. Apparently a 100 year or so tradition.
Each hiree would wear a token of their employment, i.e. a mop for a maid, a piece of straw of a thatcher, etc. and to signify being hired they would receive a Shilling's payment from their new employer for the year's employment.
There may have been a "fastpenny" payment involved as well, but as I am uncertain the exactly what that there means yet I can't elucidate.