The origin of Halloween, actually, dates back to the pagan festivals that took place in England, Scotland, Wales and Ireland several centuries ago. To this day, it is normal that on the night of October 31, children dress up as we see in the photo and go around the neighborhood asking for "trick or treating" (trick or treat in English). You have all the information in: «Customs in England«.
You have all the information in: "Customs in England".