Here in the U.S., it's apparent that the celebration of Halloween is current with Guy Fawkes Day in England. Here, the children mooching free candy say "Trick or treat!" and in that context one source links the two thusly:
"...The practice of "souling" - going from door to door on or about All Souls Day (Halloween) to solicit gifts of food in return for prayers for the dead - evolved from a pagan ritual that was practiced all over Europe, possibly as early as the 10th century. As a Christian tradition it goes back to at least the 14th century, when it is mentioned by Chaucer. It is still commonplace in many Catholic countries, notably Ireland, where soul-cakes are left out for the departed. The first reference to the practice under that name in England is John Brand's Popular Antiquities of Great Britain, 1779:
"On All Saints Day, the poor people go from parish to parish a Souling, as they call it."
The tradition has altered so that it is now children, usually dressed in disguise, who go about asking for gifts around the beginning of November. Some examples of this are from:
England, where we have requests for 'a penny for the guy'. This derives from the bonfire celebrations that began to celebrate the thwarting of the Gunpowder Plot in 1605. Guy Fawkes was the explosives specialist of the plot. He was scheduled to be hanged, drawn and quartered, but escaped that fate by prematurely hanging himself by jumping from the scaffold with the noose around his neck. He is now symbolically re-executed each year on 5th November (Bonfire Night), when effigies of him, called guys, are burned on bonfires all over England. The 'pennies' that children collect are traditionally spent on fireworks. This had a secular and political rather than religious or supernatural motivation, but it clearly inherited much from souling.
(Contd.)