There is some confusion about when twelfth night actually is. If you count the 25th as the first day of Christmas, then twelfth night is 5 January. However, others have regarded 6 January as twelfth night, partly because the day is sometimes also known as twelfth day, a celebration of importance in its own right. The 6th of January is certainly Epiphany, the date the Three Kings are said to have visited Jesus.
Before the Victorian re-imagined what Christmas was, twelfth night marked the second most important day of the Christmas season. It was a night for parties and jollity amongst all the classes and associated with drinking, eating, visiting neighbours and a brief respite from some of the normal conventions of public behaviour. A special cake with a lucky pea and bean inside it was common, the roots of both modern Christmas cake and the coins in Christmas puddings. In some parts of Britain, there were local traditions such as sporting contests, wassailing at orchards and even burning bushes or trees. It was essentially a celebration of the end of the Christmas holiday.

The shift to the Gregorian calendar in the middle of the 18th century added to the significance of 6 January. Eleven days were removed from the calendar in 1752, which meant the new 6 January was the old Christmas day and some of those angry at the change continued to celebrate Christmas itself on this day. The anger may have faded but even in the early 20th century there were people whose grandparents had celebrated the family Christmas on the sixth. Right through the Victorian period, twelfth night was also a popular date for civic Christmas balls and children’s charitable parties.
However, the Victorian period was also the time when Christmas was invented as a commercial festival and the shopping associated with this led to Christmas day becoming the culmination of celebrations rather than the start of them. The needs of an industrial society also meant people returned to work far quicker than they once had, with 25 and 26 December generally being the only days off in the late 19th century. Cakes were still eaten by some in the middle classes, and sometimes accompanied with funny rhymes and games, but the whole significance of the day was fading fast.

By the First World War, there were complaints from those who remembered the parties of their youth that twelfth night no longer meant anything but that was not true. In some areas there were conscious attempts to uphold older local traditions associated with the day. Some interwar towns continued their balls, whilst other communities shared cake and wassail bowls; folk culture was becoming widely valued, just as it was in its last throes.
Most commonly, twelfth night was associated with taking down Christmas decorations. Before the Victorians, when decorations were ivy, mistletoe and the like, it had been regarded as bad luck to either take down decorations before Candlemass (2 February) or before they had begun to wither. This superstition was a hangover from the belief that there was some kind of sprite in the decorations who would escape if not removed correctly and bring bad luck. Some people believed that the decorations should be burnt to avoid this.
As paper, glass and then plastic decorations became popular in the late nineteenth and early twentieth centuries, the superstition was transferred to these new forms. However, knowledge about why this was done could not be assumed and a 1921 magazine article felt it had to explain the superstitions to readers. There was also disagreement about whether decorations should come down on the 5th or the 6th. Nor did everyone stick to the idea of twelfth night and some decorations were taken down quickly after Boxing Day.
Walking around any town or city suggests that the majority of people no longer leave the decorations up until twelfth night and the night before returning to work or school is probably now the most common date, although not all even wait until then. Twelfth night has thus lost all its real significance but in the confusion surrounding when it is and what it signifies it is actually quite typical of Christmas traditions. We might imagine they are static and historic – and indeed that is part of their attraction – but they actually shift and alter with our changing tastes and culture.