Two more quotes (underlines mine):

(1) "Molly dancing, the local name in East Anglia for morris dancing, has been a tradition in Cambridge for well over one hundred years. It is associated with the annual Plough Monday ritual, during which young farmhands would drag a plough round the local villages, crying 'A penny for the plough boys,' and, if no penny was forthcoming, cut a furrow across the cheapskate's front lawn. As one would expect of such a 'trick-or-treat' event, the Plough Monday processional customarily took place after dark. However, during the daytime lcoal Molly dancers would tour the region, performing the local social dances on the street in somewhat rough and ready style." (From: Molly Team 'The Harpies').

(2) "What are Molly's origins?
Molly dancing is associated with the annual Plough Monday tradition (the first Monday after Twelth Night), during which young farmhands would drag a plough round the local villages, crying "a penny for the plough boys", and if no penny was forthcoming cut a furrow across the cheapskate's front lawn. As one would expect of such a "trick-or-treat" event, the Plough Monday procession usually took place after dark. However, during the daytime local Molly dancers would tour the region, dancing and collecting money/food/beer all day, then meet up in the evening for communal dancing." (From: Molly Dancing F.A.Q.)

~Masato