Some interesting local legends and traditions that take place during the Christmas season in the British Isles:
In the north of England, it was common to find a dish of mugga on the Christmas Eve table. This is a wheat porridge sweetened with honey, served up as an appetizer prior to the main meal. It was a remnant left over from Viking times.

A calennig (photo from 4.bp.blogspot.com)
In Scotland they have athol brose, a gruel made from oats. It also has whisky in it and is served as a drink. Such dishes were a practical stomach liner after the long Advent fast and before the feasting and drinking began in earnest.
In the Shetland Isles they play the game of Ba, which is street football-cum-rugby. In medieval times, street football was a traditional Christmas Day game, especially for apprentices. Banned by Lord Protector Oliver Cromwell in the 17th century, the apprentices in Canterbury rioted in protest.
In Wales there are many customs which are remnants of early Christian and even earlier Roman occupation. The calennig is an apple on three twig legs, stuck with almonds or cloves or other spiky things such as thorns. It has a sprig of evergreen at the top, and is offered to householders by caroling children, in return for a small gift of cakes, money or, more often, sweets. It was held to be a token of good crops in the coming year.
Another Welsh tradition, not always as welcome as the calennig, was known as the Mari Lwyd (translated as the Venerable Mary) . In this, the skull of a horse was arranged on a pole so that the jaws could be snapped open and shut by the bearer, who was covered by the white sheet draped from the skull. The head would carry gaily coloured streamers, perhaps symbolic reins. The horse would be joined by a group of local men and the party would proceed to call at the houses of the village. The Mari Lwyd would challenge the householder to compete with him in singing and versifying. If the Mari Lwyd could win this contest, the party would be invited inside to partake of Christmas cheer.

The Mari Lwyd (photo from forest-and-wye-today.co.uk)
As might be expected, not all households relished the company of a boisterous group dancing about with a horse's skull on a pole. The tradition began to be abandoned towards the end of the 19th century, but has since been revived in Wales.
According to an old English legend, there was once a philosophy student who fended off an attacking wild boar by choking the animal with a book on Aristotle. When the boar was dead, the student cut off its head to remove the book, then brought the head back to his college, where he and his friends had a grand feast. Soon, boar's head was a must for every English household at Christmas.

A wild boar, A damned ugly wild boar. (photo from dailymail.co.uk)
Although this legend seems to explain the popularity of the boar's head as part of the Christmas feast, a more likely explanation is that the custom is a remnant of pagan times. In some places, the German god, Frey, was considered responsible for the well-being of livestock. As Frey was symbolized by the boar, a boar was often sacrificed in hopes of a prosperous spring herd.
Like many Christmas traditions popular in medieval England, the boar's head custom eventually became impractical and died out. Boars became increasingly hard to track down and were dangerous to catch once they were found. Then, too, the week's worth of cooking and preparation required was more conducive to a well-staffed castle kitchen than that of a home. The boar's head was gradually replaced by the more familiar pork, roast beef, turkey, and goose.

Procession of the Wren Boys (picture from historyjournal.ie)
The hunting of the wren was a Celtic custom in the western and southwestern parts of the British Isles. The hunt took place on St Stephen's Day (Boxing Day). The men and boys of the village would kill a wren, hang it on a pole and carry it in a procession. It was borne to its funeral by the Wren Boys, or Droluns. Plus, everyone who gave money was presented with a feather for good luck.

Baby Jesus having a bath (picture from artprintsondemand.com)
In the mid-1550's a law was also passed by the Catholic Church that banned all pictures of the Baby Jesus having a bath. It had been a tradition for years for artists to paint Jesus having his first bath, but the Church stated that Jesus was so pure that he did not need a bath; hence it was made illegal to paint a picture of Jesus being bathed by Mary and Joseph.
Legends abound about Christmas. One involves where and when candles were first associated with Christmas. One of the more popular stories concerns the Protestant leader Martin Luther. It is said that on a journey home in the winter of 1522, he was struck by the beauty of the stars shining through the fir trees that were common where he lived in north Germany. He cut off the top of one of the smaller trees and took it home.

Martin Luther and rellies admiring his newfangled Christmas decoration (picture from myworldclassflowers.com)
Once indoors the beauty disappeared as the stars were not there. To impress his children, he put small candles on the ends of the branches to resemble the stars. Thus was born the tradition of many candles at Christmas, which were eventually replaced with strings of electric lights.
The modern Christmas tree lights are meant to represent the stars seen by Martin Luther as he journeyed home that winter's night. In that sense, Luther made his mark on our society by leading the Protestant movement in Germany in the 16th century and, so legend has it, lighting up Christmas.
Don't forget to thank him when your neighbors' house is lit up like it's in Christmas Vacation.
©scar_tissue